diff --git a/public/js/common.js b/public/js/common.js
index f5bfc8e..6d54b45 100644
--- a/public/js/common.js
+++ b/public/js/common.js
@@ -1,30 +1,37 @@
-var config = require('./config');
-var domain = config.domain; // domain name
-var urlpath = config.urlpath; // sub url path, like: www.example.com/<urlpath>
-var debug = config.debug;
-var GOOGLE_API_KEY = config.GOOGLE_API_KEY;
-var GOOGLE_CLIENT_ID = config.GOOGLE_CLIENT_ID;
-var DROPBOX_APP_KEY = config.DROPBOX_APP_KEY;
+// import config from './config';
+
+import {
+    domain, // domain name
+    urlpath, // sub url path, like: www.example.com/<urlpath>
+    debug,
+    GOOGLE_API_KEY,
+    GOOGLE_CLIENT_ID,
+    DROPBOX_APP_KEY
+} from './config';
 
 //common
-var port = window.location.port;
-window.serverurl = window.location.protocol + '//' + (domain ? domain : window.location.hostname) + (port ? ':' + port : '') + (urlpath ? '/' + urlpath : '');
-var noteid = urlpath ? window.location.pathname.slice(urlpath.length + 1, window.location.pathname.length).split('/')[1] : window.location.pathname.split('/')[1];
-var noteurl = serverurl + '/' + noteid;
+export const port = window.location.port;
+window.serverurl = `${window.location.protocol}//${domain ? domain : window.location.hostname}${port ? ':' + port : ''}${urlpath ? '/' + urlpath : ''}`;
+export const noteid = urlpath ? window.location.pathname.slice(urlpath.length + 1, window.location.pathname.length).split('/')[1] : window.location.pathname.split('/')[1];
+export const noteurl = `${serverurl}/${noteid}`;
 
-var version = '0.5.0';
+export const version = '0.5.0';
 
-var checkAuth = false;
-var profile = null;
-var lastLoginState = getLoginState();
-var lastUserId = getUserId();
-var loginStateChangeEvent = null;
+let checkAuth = false;
+let profile = null;
+let lastLoginState = getLoginState();
+let lastUserId = getUserId();
+let loginStateChangeEvent = null;
 
-function resetCheckAuth() {
+export function setloginStateChangeEvent(func) {
+    loginStateChangeEvent = func;
+}
+
+export function resetCheckAuth() {
     checkAuth = false;
 }
 
-function setLoginState(bool, id) {
+export function setLoginState(bool, id) {
     Cookies.set('loginstate', bool, {
         expires: 365
     });
@@ -40,36 +47,37 @@ function setLoginState(bool, id) {
     checkLoginStateChanged();
 }
 
-function checkLoginStateChanged() {
+export function checkLoginStateChanged() {
     if (getLoginState() != lastLoginState || getUserId() != lastUserId) {
-        if(loginStateChangeEvent)
+        if(loginStateChangeEvent) {
             loginStateChangeEvent();
+        }
         return true;
     } else {
         return false;
     }
 }
 
-function getLoginState() {
-    var state = Cookies.get('loginstate');
+export function getLoginState() {
+    const state = Cookies.get('loginstate');
     return state === "true" || state === true;
 }
 
-function getUserId() {
+export function getUserId() {
     return Cookies.get('userid');
 }
 
-function clearLoginState() {
+export function clearLoginState() {
     Cookies.remove('loginstate');
 }
 
-function checkIfAuth(yesCallback, noCallback) {
-    var cookieLoginState = getLoginState();
+export function checkIfAuth(yesCallback, noCallback) {
+    const cookieLoginState = getLoginState();
     if (checkLoginStateChanged())
         checkAuth = false;
     if (!checkAuth || typeof cookieLoginState == 'undefined') {
-        $.get(serverurl + '/me')
-            .done(function (data) {
+        $.get(`${serverurl}/me`)
+            .done(data => {
                 if (data && data.status == 'ok') {
                     profile = data;
                     yesCallback(profile);
@@ -79,10 +87,10 @@ function checkIfAuth(yesCallback, noCallback) {
                     setLoginState(false);
                 }
             })
-            .fail(function () {
+            .fail(() => {
                 noCallback();
             })
-            .always(function () {
+            .always(() => {
                 checkAuth = true;
             });
     } else if (cookieLoginState) {
@@ -92,29 +100,16 @@ function checkIfAuth(yesCallback, noCallback) {
     }
 }
 
-module.exports = {
-    domain: domain,
-    urlpath: urlpath,
-    debug: debug,
-    GOOGLE_API_KEY: GOOGLE_API_KEY,
-    GOOGLE_CLIENT_ID: GOOGLE_CLIENT_ID,
-    DROPBOX_APP_KEY: DROPBOX_APP_KEY,
-    port: port,
-    noteid: noteid,
-    noteurl: noteurl,
-    version: version,
-    checkAuth: checkAuth,
-    profile: profile,
-    lastLoginState: lastLoginState,
-    lastUserId: lastUserId,
-    loginStateChangeEvent: loginStateChangeEvent,
-
-    /* export functions */
-    resetCheckAuth: resetCheckAuth,
-    setLoginState: setLoginState,
-    checkLoginStateChanged: checkLoginStateChanged,
-    getLoginState: getLoginState,
-    getUserId: getUserId,
-    clearLoginState: clearLoginState,
-    checkIfAuth: checkIfAuth
+export default {
+    domain,
+    urlpath,
+    debug,
+    GOOGLE_API_KEY,
+    GOOGLE_CLIENT_ID,
+    DROPBOX_APP_KEY,
+    checkAuth,
+    profile,
+    lastLoginState,
+    lastUserId,
+    loginStateChangeEvent
 };
diff --git a/public/js/cover.js b/public/js/cover.js
index b888684..677d82e 100644
--- a/public/js/cover.js
+++ b/public/js/cover.js
@@ -3,30 +3,31 @@ require('./locale');
 require('../css/cover.css');
 require('../css/site.css');
 
-var common = require('./common');
-var checkIfAuth = common.checkIfAuth;
-var urlpath = common.urlpath;
-var resetCheckAuth = common.resetCheckAuth;
-var getLoginState = common.getLoginState;
-var clearLoginState = common.clearLoginState;
-var loginStateChangeEvent = common.loginStateChangeEvent;
+import {
+    checkIfAuth,
+    clearLoginState,
+    getLoginState,
+    resetCheckAuth,
+    setloginStateChangeEvent
+} from './common';
 
-var historyModule = require('./history');
-var parseStorageToHistory = historyModule.parseStorageToHistory;
-var parseHistory = historyModule.parseHistory;
-var getStorageHistory = historyModule.getStorageHistory;
-var getHistory = historyModule.getHistory;
-var saveHistory = historyModule.saveHistory;
-var removeHistory = historyModule.removeHistory;
-var postHistoryToServer = historyModule.postHistoryToServer;
-var deleteServerHistory = historyModule.deleteServerHistory;
-var parseServerToHistory = historyModule.parseServerToHistory;
-var saveStorageHistoryToServer = historyModule.saveStorageHistoryToServer;
-var clearDuplicatedHistory = historyModule.clearDuplicatedHistory;
+import {
+    clearDuplicatedHistory,
+    deleteServerHistory,
+    getHistory,
+    getStorageHistory,
+    parseHistory,
+    parseServerToHistory,
+    parseStorageToHistory,
+    postHistoryToServer,
+    removeHistory,
+    saveHistory,
+    saveStorageHistoryToServer
+} from './history';
 
-var saveAs = require('file-saver').saveAs;
-var List = require('list.js');
-var S = require('string');
+import { saveAs } from 'file-saver';
+import List from 'list.js';
+import S from 'string';
 
 import Cover from './views/Cover';
 import Vue from 'vue';
@@ -36,13 +37,13 @@ new Vue({
     render: (h) => h(Cover)
 })
 
-var options = {
+const options = {
     valueNames: ['id', 'text', 'timestamp', 'fromNow', 'time', 'tags', 'pinned'],
     item: '<li class="col-xs-12 col-sm-6 col-md-6 col-lg-4">\
             <span class="id" style="display:none;"></span>\
             <a href="#">\
                 <div class="item">\
-					<div class="ui-history-pin fa fa-thumb-tack fa-fw"></div>\
+                    <div class="ui-history-pin fa fa-thumb-tack fa-fw"></div>\
                     <div class="ui-history-close fa fa-close fa-fw" data-toggle="modal" data-target=".delete-modal"></div>\
                     <div class="content">\
                         <h4 class="text"></h4>\
@@ -64,15 +65,16 @@ var options = {
         })
     ]
 };
-var historyList = new List('history', options);
+const historyList = new List('history', options);
 
 migrateHistoryFromTempCallback = pageInit;
-loginStateChangeEvent = pageInit;
+setloginStateChangeEvent(pageInit);
+
 pageInit();
 
 function pageInit() {
     checkIfAuth(
-        function (data) {
+        data => {
             $('.ui-signin').hide();
             $('.ui-or').hide();
             $('.ui-welcome').show();
@@ -83,7 +85,7 @@ function pageInit() {
             $(".ui-history").click();
             parseServerToHistory(historyList, parseHistoryCallback);
         },
-        function () {
+        () => {
             $('.ui-signin').show();
             $('.ui-or').show();
             $('.ui-welcome').hide();
@@ -100,14 +102,14 @@ $(".masthead-nav li").click(function () {
     $(this).addClass("active");
 });
 
-$(".ui-home").click(function () {
+$(".ui-home").click(() => {
     if (!$("#home").is(':visible')) {
         $(".section:visible").hide();
         $("#home").fadeIn();
     }
 });
 
-$(".ui-history").click(function () {
+$(".ui-history").click(() => {
     if (!$("#history").is(':visible')) {
         $(".section:visible").hide();
         $("#history").fadeIn();
@@ -120,7 +122,7 @@ function checkHistoryList() {
         $(".ui-import-from-browser").hide();
     } else if ($("#history-list").children().length == 0) {
         $(".ui-nohistory").slideDown();
-        getStorageHistory(function (data) {
+        getStorageHistory(data => {
             if (data && data.length > 0 && getLoginState() && historyList.items.length == 0) {
                 $(".ui-import-from-browser").slideDown();
             }
@@ -130,35 +132,35 @@ function checkHistoryList() {
 
 function parseHistoryCallback(list, notehistory) {
     checkHistoryList();
-	//sort by pinned then timestamp
-	list.sort('', {
-        sortFunction: function (a, b) {
-			var notea = a.values();
-            var noteb = b.values();
-			if (notea.pinned && !noteb.pinned) {
+    //sort by pinned then timestamp
+    list.sort('', {
+        sortFunction(a, b) {
+            const notea = a.values();
+            const noteb = b.values();
+            if (notea.pinned && !noteb.pinned) {
                 return -1;
             } else if (!notea.pinned && noteb.pinned) {
                 return 1;
             } else {
-				if (notea.timestamp > noteb.timestamp) {
-                	return -1;
-				} else if (notea.timestamp < noteb.timestamp) {
-					return 1;
-				} else {
-					return 0;
-				}
-			}
-		}
-	});
+                if (notea.timestamp > noteb.timestamp) {
+                    return -1;
+                } else if (notea.timestamp < noteb.timestamp) {
+                    return 1;
+                } else {
+                    return 0;
+                }
+            }
+        }
+    });
     // parse filter tags
-    var filtertags = [];
-    for (var i = 0, l = list.items.length; i < l; i++) {
-        var tags = list.items[i]._values.tags;
+    const filtertags = [];
+    for (let i = 0, l = list.items.length; i < l; i++) {
+        const tags = list.items[i]._values.tags;
         if (tags && tags.length > 0) {
-            for (var j = 0; j < tags.length; j++) {
+            for (let j = 0; j < tags.length; j++) {
                 //push info filtertags if not found
-                var found = false;
-                if (filtertags.indexOf(tags[j]) != -1)
+                let found = false;
+                if (filtertags.includes(tags[j]))
                     found = true;
                 if (!found)
                     filtertags.push(tags[j]);
@@ -169,17 +171,17 @@ function parseHistoryCallback(list, notehistory) {
 }
 
 // update items whenever list updated
-historyList.on('updated', function (e) {
-    for (var i = 0, l = e.items.length; i < l; i++) {
-        var item = e.items[i];
+historyList.on('updated', e => {
+    for (let i = 0, l = e.items.length; i < l; i++) {
+        const item = e.items[i];
         if (item.visible()) {
-            var itemEl = $(item.elm);
-            var values = item._values;
-            var a = itemEl.find("a");
-            var pin = itemEl.find(".ui-history-pin");
-            var tagsEl = itemEl.find(".tags");
+            const itemEl = $(item.elm);
+            const values = item._values;
+            const a = itemEl.find("a");
+            const pin = itemEl.find(".ui-history-pin");
+            const tagsEl = itemEl.find(".tags");
             //parse link to element a
-            a.attr('href', serverurl + '/' + values.id);
+            a.attr('href', `${serverurl}/${values.id}`);
             //parse pinned
             if (values.pinned) {
                 pin.addClass('active');
@@ -187,12 +189,12 @@ historyList.on('updated', function (e) {
                 pin.removeClass('active');
             }
             //parse tags
-            var tags = values.tags;
+            const tags = values.tags;
             if (tags && tags.length > 0 && tagsEl.children().length <= 0) {
-                var labels = [];
-                for (var j = 0; j < tags.length; j++) {
+                const labels = [];
+                for (let j = 0; j < tags.length; j++) {
                     //push into the item label
-                    labels.push("<span class='label label-default'>" + tags[j] + "</span>");
+                    labels.push(`<span class='label label-default'>${tags[j]}</span>`);
                 }
                 tagsEl.html(labels.join(' '));
             }
@@ -206,21 +208,21 @@ historyList.on('updated', function (e) {
 
 function historyCloseClick(e) {
     e.preventDefault();
-    var id = $(this).closest("a").siblings("span").html();
-    var value = historyList.get('id', id)[0]._values;
+    const id = $(this).closest("a").siblings("span").html();
+    const value = historyList.get('id', id)[0]._values;
     $('.ui-delete-modal-msg').text('Do you really want to delete below history?');
-    $('.ui-delete-modal-item').html('<i class="fa fa-file-text"></i> ' + value.text + '<br><i class="fa fa-clock-o"></i> ' + value.time);
+    $('.ui-delete-modal-item').html(`<i class="fa fa-file-text"></i> ${value.text}<br><i class="fa fa-clock-o"></i> ${value.time}`);
     clearHistory = false;
     deleteId = id;
 }
 
 function historyPinClick(e) {
     e.preventDefault();
-    var $this = $(this);
-    var id = $this.closest("a").siblings("span").html();
-    var item = historyList.get('id', id)[0];
-    var values = item._values;
-    var pinned = values.pinned;
+    const $this = $(this);
+    const id = $this.closest("a").siblings("span").html();
+    const item = historyList.get('id', id)[0];
+    const values = item._values;
+    let pinned = values.pinned;
     if (!values.pinned) {
         pinned = true;
         item._values.pinned = true;
@@ -228,10 +230,10 @@ function historyPinClick(e) {
         pinned = false;
         item._values.pinned = false;
     }
-    checkIfAuth(function () {
+    checkIfAuth(() => {
         postHistoryToServer(id, {
-            pinned: pinned
-        }, function (err, result) {
+            pinned
+        }, (err, result) => {
             if (!err) {
                 if (pinned)
                     $this.addClass('active');
@@ -239,9 +241,9 @@ function historyPinClick(e) {
                     $this.removeClass('active');
             }
         });
-    }, function () {
-        getHistory(function (notehistory) {
-            for(var i = 0; i < notehistory.length; i++) {
+    }, () => {
+        getHistory(notehistory => {
+            for(let i = 0; i < notehistory.length; i++) {
                 if (notehistory[i].id == id) {
                     notehistory[i].pinned = pinned;
                     break;
@@ -260,10 +262,10 @@ function historyPinClick(e) {
 setInterval(updateItemFromNow, 60000);
 
 function updateItemFromNow() {
-    var items = $('.item').toArray();
-    for (var i = 0; i < items.length; i++) {
-        var item = $(items[i]);
-        var timestamp = parseInt(item.find('.timestamp').text());
+    const items = $('.item').toArray();
+    for (let i = 0; i < items.length; i++) {
+        const item = $(items[i]);
+        const timestamp = parseInt(item.find('.timestamp').text());
         item.find('.fromNow').text(moment(timestamp).fromNow());
     }
 }
@@ -272,8 +274,8 @@ var clearHistory = false;
 var deleteId = null;
 
 function deleteHistory() {
-    checkIfAuth(function () {
-        deleteServerHistory(deleteId, function (err, result) {
+    checkIfAuth(() => {
+        deleteServerHistory(deleteId, (err, result) => {
             if (!err) {
                 if (clearHistory) {
                     historyList.clear();
@@ -287,7 +289,7 @@ function deleteHistory() {
             deleteId = null;
             clearHistory = false;
         });
-    }, function () {
+    }, () => {
         if (clearHistory) {
             saveHistory([]);
             historyList.clear();
@@ -295,8 +297,8 @@ function deleteHistory() {
             deleteId = null;
         } else {
             if (!deleteId) return;
-            getHistory(function (notehistory) {
-                var newnotehistory = removeHistory(deleteId, notehistory);
+            getHistory(notehistory => {
+                const newnotehistory = removeHistory(deleteId, notehistory);
                 saveHistory(newnotehistory);
                 historyList.remove('id', deleteId);
                 checkHistoryList();
@@ -308,36 +310,36 @@ function deleteHistory() {
     });
 }
 
-$(".ui-delete-modal-confirm").click(function () {
+$(".ui-delete-modal-confirm").click(() => {
     deleteHistory();
 });
 
-$(".ui-import-from-browser").click(function () {
-    saveStorageHistoryToServer(function () {
+$(".ui-import-from-browser").click(() => {
+    saveStorageHistoryToServer(() => {
         parseStorageToHistory(historyList, parseHistoryCallback);
     });
 });
 
-$(".ui-save-history").click(function () {
-    getHistory(function (data) {
-        var history = JSON.stringify(data);
-        var blob = new Blob([history], {
+$(".ui-save-history").click(() => {
+    getHistory(data => {
+        const history = JSON.stringify(data);
+        const blob = new Blob([history], {
             type: "application/json;charset=utf-8"
         });
-        saveAs(blob, 'hackmd_history_' + moment().format('YYYYMMDDHHmmss'));
+        saveAs(blob, `hackmd_history_${moment().format('YYYYMMDDHHmmss')}`);
     });
 });
 
-$(".ui-open-history").bind("change", function (e) {
-    var files = e.target.files || e.dataTransfer.files;
-    var file = files[0];
-    var reader = new FileReader();
-    reader.onload = function () {
-        var notehistory = JSON.parse(reader.result);
+$(".ui-open-history").bind("change", e => {
+    const files = e.target.files || e.dataTransfer.files;
+    const file = files[0];
+    const reader = new FileReader();
+    reader.onload = () => {
+        const notehistory = JSON.parse(reader.result);
         //console.log(notehistory);
         if (!reader.result) return;
-        getHistory(function (data) {
-            var mergedata = data.concat(notehistory);
+        getHistory(data => {
+            let mergedata = data.concat(notehistory);
             mergedata = clearDuplicatedHistory(mergedata);
             saveHistory(mergedata);
             parseHistory(historyList, parseHistoryCallback);
@@ -347,18 +349,18 @@ $(".ui-open-history").bind("change", function (e) {
     reader.readAsText(file);
 });
 
-$(".ui-clear-history").click(function () {
+$(".ui-clear-history").click(() => {
     $('.ui-delete-modal-msg').text('Do you really want to clear all history?');
     $('.ui-delete-modal-item').html('There is no turning back.');
     clearHistory = true;
     deleteId = null;
 });
 
-$(".ui-refresh-history").click(function () {
-    var lastTags = $(".ui-use-tags").select2('val');
+$(".ui-refresh-history").click(() => {
+    const lastTags = $(".ui-use-tags").select2('val');
     $(".ui-use-tags").select2('val', '');
     historyList.filter();
-    var lastKeyword = $('.search').val();
+    const lastKeyword = $('.search').val();
     $('.search').val('');
     historyList.search();
     $('#history-list').slideUp('fast');
@@ -366,7 +368,7 @@ $(".ui-refresh-history").click(function () {
 
     resetCheckAuth();
     historyList.clear();
-    parseHistory(historyList, function (list, notehistory) {
+    parseHistory(historyList, (list, notehistory) => {
         parseHistoryCallback(list, notehistory);
         $(".ui-use-tags").select2('val', lastTags);
         $(".ui-use-tags").trigger('change');
@@ -378,16 +380,16 @@ $(".ui-refresh-history").click(function () {
     });
 });
 
-$(".ui-logout").click(function () {
+$(".ui-logout").click(() => {
     clearLoginState();
-    location.href = serverurl + '/logout';
+    location.href = `${serverurl}/logout`;
 });
 
-var filtertags = [];
+let filtertags = [];
 $(".ui-use-tags").select2({
     placeholder: $(".ui-use-tags").attr('placeholder'),
     multiple: true,
-    data: function () {
+    data() {
         return {
             results: filtertags
         };
@@ -397,7 +399,7 @@ $('.select2-input').css('width', 'inherit');
 buildTagsFilter([]);
 
 function buildTagsFilter(tags) {
-    for (var i = 0; i < tags.length; i++)
+    for (let i = 0; i < tags.length; i++)
         tags[i] = {
             id: i,
             text: S(tags[i]).unescapeHTML().s
@@ -405,17 +407,17 @@ function buildTagsFilter(tags) {
     filtertags = tags;
 }
 $(".ui-use-tags").on('change', function () {
-    var tags = [];
-    var data = $(this).select2('data');
-    for (var i = 0; i < data.length; i++)
+    const tags = [];
+    const data = $(this).select2('data');
+    for (let i = 0; i < data.length; i++)
         tags.push(data[i].text);
     if (tags.length > 0) {
-        historyList.filter(function (item) {
-            var values = item.values();
+        historyList.filter(item => {
+            const values = item.values();
             if (!values.tags) return false;
-            var found = false;
-            for (var i = 0; i < tags.length; i++) {
-                if (values.tags.indexOf(tags[i]) != -1) {
+            let found = false;
+            for (let i = 0; i < tags.length; i++) {
+                if (values.tags.includes(tags[i])) {
                     found = true;
                     break;
                 }
@@ -428,6 +430,6 @@ $(".ui-use-tags").on('change', function () {
     checkHistoryList();
 });
 
-$('.search').keyup(function () {
+$('.search').keyup(() => {
     checkHistoryList();
 });
diff --git a/public/js/extra.js b/public/js/extra.js
index ba61a66..f1681b2 100644
--- a/public/js/extra.js
+++ b/public/js/extra.js
@@ -1,15 +1,17 @@
 require('prismjs/themes/prism.css');
-
-var Prism = require('prismjs');
 require('prismjs/components/prism-wiki');
 require('prismjs/components/prism-haskell');
 require('prismjs/components/prism-go');
 require('prismjs/components/prism-typescript');
 require('prismjs/components/prism-jsx');
-var hljs = require('highlight.js');
-var PDFObject = require('pdfobject');
-var S = require('string');
-var saveAs = require('file-saver').saveAs;
+
+import Prism from 'prismjs';
+import hljs from 'highlight.js';
+import PDFObject from 'pdfobject';
+import S from 'string';
+import { saveAs } from 'file-saver';
+
+require('./common');
 require('../vendor/md-toc');
 
 //auto update last change
@@ -21,9 +23,10 @@ window.lastchangeui = {
     user: $(".ui-lastchangeuser"),
     nouser: $(".ui-no-lastchangeuser")
 }
-var ownerui = $(".ui-owner");
 
-function updateLastChange() {
+const ownerui = $(".ui-owner");
+
+export function updateLastChange() {
     if (!lastchangeui) return;
     if (createtime) {
         if (createtime && !lastchangetime) {
@@ -31,7 +34,7 @@ function updateLastChange() {
         } else {
             lastchangeui.status.text('changed');
         }
-        var time = lastchangetime || createtime;
+        const time = lastchangetime || createtime;
         lastchangeui.time.html(moment(time).fromNow());
         lastchangeui.time.attr('title', moment(time).format('llll'));
     }
@@ -40,13 +43,14 @@ setInterval(updateLastChange, 60000);
 
 window.lastchangeuser = null;
 window.lastchangeuserprofile = null;
-function updateLastChangeUser() {
+
+export function updateLastChangeUser() {
     if (lastchangeui) {
       if (lastchangeuser && lastchangeuserprofile) {
-          var icon = lastchangeui.user.children('i');
+          const icon = lastchangeui.user.children('i');
           icon.attr('title', lastchangeuserprofile.name).tooltip('fixTitle');
           if (lastchangeuserprofile.photo)
-              icon.attr('style', 'background-image:url(' + lastchangeuserprofile.photo + ')');
+              icon.attr('style', `background-image:url(${lastchangeuserprofile.photo})`);
           lastchangeui.user.show();
           lastchangeui.nouser.hide();
       } else {
@@ -58,12 +62,13 @@ function updateLastChangeUser() {
 
 window.owner = null;
 window.ownerprofile = null;
-function updateOwner() {
+
+export function updateOwner() {
     if (ownerui) {
       if (owner && ownerprofile && owner !== lastchangeuser) {
-          var icon = ownerui.children('i');
+          const icon = ownerui.children('i');
           icon.attr('title', ownerprofile.name).tooltip('fixTitle');
-          var styleString = 'background-image:url(' + ownerprofile.photo + ')';
+          const styleString = `background-image:url(${ownerprofile.photo})`;
           if (ownerprofile.photo && icon.attr('style') !== styleString)
               icon.attr('style', styleString);
           ownerui.show();
@@ -75,11 +80,11 @@ function updateOwner() {
 
 //get title
 function getTitle(view) {
-    var title = "";
+    let title = "";
     if (md && md.meta && md.meta.title && (typeof md.meta.title == "string" || typeof md.meta.title == "number")) {
         title = md.meta.title;
     } else {
-        var h1s = view.find("h1");
+        const h1s = view.find("h1");
         if (h1s.length > 0) {
             title = h1s.first().text();
         } else {
@@ -90,8 +95,8 @@ function getTitle(view) {
 }
 
 //render title
-function renderTitle(view) {
-    var title = getTitle(view);
+export function renderTitle(view) {
+    let title = getTitle(view);
     if (title) {
         title += ' - HackMD';
     } else {
@@ -101,8 +106,8 @@ function renderTitle(view) {
 }
 
 //render filename
-function renderFilename(view) {
-    var filename = getTitle(view);
+export function renderFilename(view) {
+    let filename = getTitle(view);
     if (!filename) {
         filename = 'Untitled';
     }
@@ -110,29 +115,29 @@ function renderFilename(view) {
 }
 
 // render tags
-function renderTags(view) {
-    var tags = [];
-    var rawtags = [];
+export function renderTags(view) {
+    const tags = [];
+    const rawtags = [];
     if (md && md.meta && md.meta.tags && (typeof md.meta.tags == "string" || typeof md.meta.tags == "number")) {
-        var metaTags = ('' + md.meta.tags).split(',');
+        const metaTags = (`${md.meta.tags}`).split(',');
         for (var i = 0; i < metaTags.length; i++) {
-            var text = metaTags[i].trim();
+            const text = metaTags[i].trim();
             if (text) rawtags.push(text);
         }
     } else {
-        view.find('h6').each(function (key, value) {
+        view.find('h6').each((key, value) => {
             if (/^tags/gmi.test($(value).text())) {
-                var codes = $(value).find("code");
-                for (var i = 0; i < codes.length; i++) {
-                    var text = codes[i].innerHTML.trim();
+                const codes = $(value).find("code");
+                for (let i = 0; i < codes.length; i++) {
+                    const text = codes[i].innerHTML.trim();
                     if (text) rawtags.push(text);
                 }
             }
         });
     }
     for (var i = 0; i < rawtags.length; i++) {
-        var found = false;
-        for (var j = 0; j < tags.length; j++) {
+        let found = false;
+        for (let j = 0; j < tags.length; j++) {
             if (tags[j] == rawtags[i]) {
                 found = true;
                 break;
@@ -145,13 +150,13 @@ function renderTags(view) {
 }
 
 function slugifyWithUTF8(text) {
-    var newText = S(text.toLowerCase()).trim().stripTags().dasherize().s;
+    let newText = S(text.toLowerCase()).trim().stripTags().dasherize().s;
     newText = newText.replace(/([\!\"\#\$\%\&\'\(\)\*\+\,\.\/\:\;\<\=\>\?\@\[\\\]\^\`\{\|\}\~])/g, '');
     return newText;
 }
 
-function isValidURL(str) {
-    var pattern = new RegExp('^(https?:\\/\\/)?' + // protocol
+export function isValidURL(str) {
+    const pattern = new RegExp('^(https?:\\/\\/)?' + // protocol
         '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|' + // domain name
         '((\\d{1,3}\\.){3}\\d{1,3}))' + // OR ip (v4) address
         '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*' + // port and path
@@ -165,12 +170,12 @@ function isValidURL(str) {
 }
 
 //parse meta
-function parseMeta(md, edit, view, toc, tocAffix) {
-    var lang = null;
-    var dir = null;
-    var breaks = true;
+export function parseMeta(md, edit, view, toc, tocAffix) {
+    let lang = null;
+    let dir = null;
+    let breaks = true;
     if (md && md.meta) {
-        var meta = md.meta;
+        const meta = md.meta;
         lang = meta.lang;
         dir = meta.dir;
         breaks = meta.breaks;
@@ -210,13 +215,13 @@ function parseMeta(md, edit, view, toc, tocAffix) {
 window.viewAjaxCallback = null;
 
 //regex for extra tags
-var spaceregex = /\s*/;
-var notinhtmltagregex = /(?![^<]*>|[^<>]*<\/)/;
-var coloregex = /\[color=([#|\(|\)|\s|\,|\w]*?)\]/;
+const spaceregex = /\s*/;
+const notinhtmltagregex = /(?![^<]*>|[^<>]*<\/)/;
+let coloregex = /\[color=([#|\(|\)|\s|\,|\w]*?)\]/;
 coloregex = new RegExp(coloregex.source + notinhtmltagregex.source, "g");
-var nameregex = /\[name=(.*?)\]/;
-var timeregex = /\[time=([:|,|+|-|\(|\)|\s|\w]*?)\]/;
-var nameandtimeregex = new RegExp(nameregex.source + spaceregex.source + timeregex.source + notinhtmltagregex.source, "g");
+let nameregex = /\[name=(.*?)\]/;
+let timeregex = /\[time=([:|,|+|-|\(|\)|\s|\w]*?)\]/;
+const nameandtimeregex = new RegExp(nameregex.source + spaceregex.source + timeregex.source + notinhtmltagregex.source, "g");
 nameregex = new RegExp(nameregex.source + notinhtmltagregex.source, "g");
 timeregex = new RegExp(timeregex.source + notinhtmltagregex.source, "g");
 
@@ -231,35 +236,36 @@ function replaceExtraTags(html) {
 if (typeof mermaid !== 'undefined' && mermaid) mermaid.startOnLoad = false;
 
 //dynamic event or object binding here
-function finishView(view) {
+export function finishView(view) {
     //todo list
-    var lis = view.find('li.raw').removeClass("raw").sortByDepth().toArray();
-    for (var i = 0; i < lis.length; i++) {
-        var li = lis[i];
-        var html = $(li).clone()[0].innerHTML;
-        var p = $(li).children('p');
+    const lis = view.find('li.raw').removeClass("raw").sortByDepth().toArray();
+
+    for (let li of lis) {
+        let html = $(li).clone()[0].innerHTML;
+        const p = $(li).children('p');
         if (p.length == 1) {
             html = p.html();
             li = p[0];
         }
         html = replaceExtraTags(html);
         li.innerHTML = html;
-        var disabled = 'disabled';
+        let disabled = 'disabled';
         if(typeof editor !== 'undefined' && havePermission())
             disabled = '';
         if (/^\s*\[[x ]\]\s*/.test(html)) {
-            li.innerHTML = html.replace(/^\s*\[ \]\s*/, '<input type="checkbox" class="task-list-item-checkbox "' + disabled + '><label></label>')
-                .replace(/^\s*\[x\]\s*/, '<input type="checkbox" class="task-list-item-checkbox" checked ' + disabled + '><label></label>');
-            lis[i].setAttribute('class', 'task-list-item');
+            li.innerHTML = html.replace(/^\s*\[ \]\s*/, `<input type="checkbox" class="task-list-item-checkbox "${disabled}><label></label>`)
+                .replace(/^\s*\[x\]\s*/, `<input type="checkbox" class="task-list-item-checkbox" checked ${disabled}><label></label>`);
+            li.setAttribute('class', 'task-list-item');
         }
         if (typeof editor !== 'undefined' && havePermission())
             $(li).find('input').change(toggleTodoEvent);
         //color tag in list will convert it to tag icon with color
-        var tag_color = $(li).closest('ul').find(".color");
-        tag_color.each(function (key, value) {
+        const tag_color = $(li).closest('ul').find(".color");
+        tag_color.each((key, value) => {
             $(value).addClass('fa fa-tag').css('color', $(value).attr('data-color'));
         });
     }
+
     //youtube
     view.find("div.youtube.raw").removeClass("raw")
         .click(function () {
@@ -270,41 +276,41 @@ function finishView(view) {
         .click(function () {
             imgPlayiframe(this, '//player.vimeo.com/video/');
         })
-        .each(function (key, value) {
+        .each((key, value) => {
             $.ajax({
                 type: 'GET',
-                url: '//vimeo.com/api/v2/video/' + $(value).attr('data-videoid') + '.json',
+                url: `//vimeo.com/api/v2/video/${$(value).attr('data-videoid')}.json`,
                 jsonp: 'callback',
                 dataType: 'jsonp',
-                success: function (data) {
-                    var thumbnail_src = data[0].thumbnail_large;
-                    var image = '<img src="' + thumbnail_src + '" />';
+                success(data) {
+                    const thumbnail_src = data[0].thumbnail_large;
+                    const image = `<img src="${thumbnail_src}" />`;
                     $(value).prepend(image);
                     if(viewAjaxCallback) viewAjaxCallback();
                 }
             });
         });
     //gist
-    view.find("code[data-gist-id]").each(function (key, value) {
+    view.find("code[data-gist-id]").each((key, value) => {
         if ($(value).children().length == 0)
             $(value).gist(viewAjaxCallback);
     });
     //sequence diagram
-    var sequences = view.find("div.sequence-diagram.raw").removeClass("raw");
-    sequences.each(function (key, value) {
+    const sequences = view.find("div.sequence-diagram.raw").removeClass("raw");
+    sequences.each((key, value) => {
         try {
             var $value = $(value);
-            var $ele = $(value).parent().parent();
+            const $ele = $(value).parent().parent();
 
-            var sequence = $value;
+            const sequence = $value;
             sequence.sequenceDiagram({
                 theme: 'simple'
             });
 
             $ele.addClass('sequence-diagram');
             $value.children().unwrap().unwrap();
-            var svg = $ele.find('> svg');
-            svg[0].setAttribute('viewBox', '0 0 ' + svg.attr('width') + ' ' + svg.attr('height'));
+            const svg = $ele.find('> svg');
+            svg[0].setAttribute('viewBox', `0 0 ${svg.attr('width')} ${svg.attr('height')}`);
             svg[0].setAttribute('preserveAspectRatio', 'xMidYMid meet');
         } catch (err) {
             $value.unwrap();
@@ -312,13 +318,13 @@ function finishView(view) {
         }
     });
     //flowchart
-    var flow = view.find("div.flow-chart.raw").removeClass("raw");
-    flow.each(function (key, value) {
+    const flow = view.find("div.flow-chart.raw").removeClass("raw");
+    flow.each((key, value) => {
         try {
             var $value = $(value);
-            var $ele = $(value).parent().parent();
+            const $ele = $(value).parent().parent();
 
-            var chart = flowchart.parse($value.text());
+            const chart = flowchart.parse($value.text());
             $value.html('');
             chart.drawSVG(value, {
                 'line-width': 2,
@@ -335,14 +341,14 @@ function finishView(view) {
         }
     });
     //graphviz
-    var Viz = require("viz.js");
-    var graphvizs = view.find("div.graphviz.raw").removeClass("raw");
-    graphvizs.each(function (key, value) {
+    const Viz = require("viz.js");
+    const graphvizs = view.find("div.graphviz.raw").removeClass("raw");
+    graphvizs.each((key, value) => {
         try {
             var $value = $(value);
-            var $ele = $(value).parent().parent();
+            const $ele = $(value).parent().parent();
 
-            var graphviz = Viz($value.text());
+            const graphviz = Viz($value.text());
             if (!graphviz) throw Error('viz.js output empty graph');
             $value.html(graphviz);
 
@@ -354,14 +360,14 @@ function finishView(view) {
         }
     });
     //mermaid
-    var mermaids = view.find("div.mermaid.raw").removeClass("raw");
-    mermaids.each(function (key, value) {
+    const mermaids = view.find("div.mermaid.raw").removeClass("raw");
+    mermaids.each((key, value) => {
         try {
             var $value = $(value);
-            var $ele = $(value).closest('pre');
+            const $ele = $(value).closest('pre');
 
-            var mermaidError = null;
-            mermaid.parseError = function (err, hash) {
+            let mermaidError = null;
+            mermaid.parseError = (err, hash) => {
                 mermaidError = err;
             };
 
@@ -379,44 +385,44 @@ function finishView(view) {
         }
     });
     //image href new window(emoji not included)
-    var images = view.find("img.raw[src]").removeClass("raw");
-    images.each(function (key, value) {
+    const images = view.find("img.raw[src]").removeClass("raw");
+    images.each((key, value) => {
         // if it's already wrapped by link, then ignore
-        var $value = $(value);
-        $value[0].onload = function (e) {
+        const $value = $(value);
+        $value[0].onload = e => {
             if(viewAjaxCallback) viewAjaxCallback();
         };
     });
     //blockquote
-    var blockquote = view.find("blockquote.raw").removeClass("raw");
-    var blockquote_p = blockquote.find("p");
-    blockquote_p.each(function (key, value) {
-        var html = $(value).html();
+    const blockquote = view.find("blockquote.raw").removeClass("raw");
+    const blockquote_p = blockquote.find("p");
+    blockquote_p.each((key, value) => {
+        let html = $(value).html();
         html = replaceExtraTags(html);
         $(value).html(html);
     });
     //color tag in blockquote will change its left border color
-    var blockquote_color = blockquote.find(".color");
-    blockquote_color.each(function (key, value) {
+    const blockquote_color = blockquote.find(".color");
+    blockquote_color.each((key, value) => {
         $(value).closest("blockquote").css('border-left-color', $(value).attr('data-color'));
     });
     //slideshare
     view.find("div.slideshare.raw").removeClass("raw")
-        .each(function (key, value) {
+        .each((key, value) => {
             $.ajax({
                 type: 'GET',
-                url: '//www.slideshare.net/api/oembed/2?url=http://www.slideshare.net/' + $(value).attr('data-slideshareid') + '&format=json',
+                url: `//www.slideshare.net/api/oembed/2?url=http://www.slideshare.net/${$(value).attr('data-slideshareid')}&format=json`,
                 jsonp: 'callback',
                 dataType: 'jsonp',
-                success: function (data) {
-                    var $html = $(data.html);
-                    var iframe = $html.closest('iframe');
-                    var caption = $html.closest('div');
-                    var inner = $('<div class="inner"></div>').append(iframe);
-                    var height = iframe.attr('height');
-                    var width = iframe.attr('width');
-                    var ratio = (height / width) * 100;
-                    inner.css('padding-bottom', ratio + '%');
+                success(data) {
+                    const $html = $(data.html);
+                    const iframe = $html.closest('iframe');
+                    const caption = $html.closest('div');
+                    const inner = $('<div class="inner"></div>').append(iframe);
+                    const height = iframe.attr('height');
+                    const width = iframe.attr('width');
+                    const ratio = (height / width) * 100;
+                    inner.css('padding-bottom', `${ratio}%`);
                     $(value).html(inner).append(caption);
                     if(viewAjaxCallback) viewAjaxCallback();
                 }
@@ -424,31 +430,31 @@ function finishView(view) {
         });
     //speakerdeck
     view.find("div.speakerdeck.raw").removeClass("raw")
-        .each(function (key, value) {
-            var url = 'https://speakerdeck.com/oembed.json?url=https%3A%2F%2Fspeakerdeck.com%2F' + encodeURIComponent($(value).attr('data-speakerdeckid'));
+        .each((key, value) => {
+            const url = `https://speakerdeck.com/oembed.json?url=https%3A%2F%2Fspeakerdeck.com%2F${encodeURIComponent($(value).attr('data-speakerdeckid'))}`;
             //use yql because speakerdeck not support jsonp
             $.ajax({
                 url: 'https://query.yahooapis.com/v1/public/yql',
                 data: {
-                    q: "select * from json where url ='" + url + "'",
+                    q: `select * from json where url ='${url}'`,
                     format: "json"
                 },
                 dataType: "jsonp",
-                success: function (data) {
+                success(data) {
                     if (!data.query || !data.query.results) return;
-                    var json = data.query.results.json;
-                    var html = json.html;
+                    const json = data.query.results.json;
+                    const html = json.html;
                     var ratio = json.height / json.width;
                     $(value).html(html);
-                    var iframe = $(value).children('iframe');
-                    var src = iframe.attr('src');
+                    const iframe = $(value).children('iframe');
+                    const src = iframe.attr('src');
                     if (src.indexOf('//') == 0)
-                        iframe.attr('src', 'https:' + src);
-                    var inner = $('<div class="inner"></div>').append(iframe);
-                    var height = iframe.attr('height');
-                    var width = iframe.attr('width');
+                        iframe.attr('src', `https:${src}`);
+                    const inner = $('<div class="inner"></div>').append(iframe);
+                    const height = iframe.attr('height');
+                    const width = iframe.attr('width');
                     var ratio = (height / width) * 100;
-                    inner.css('padding-bottom', ratio + '%');
+                    inner.css('padding-bottom', `${ratio}%`);
                     $(value).html(inner);
                     if(viewAjaxCallback) viewAjaxCallback();
                 }
@@ -457,8 +463,8 @@ function finishView(view) {
     //pdf
     view.find("div.pdf.raw").removeClass("raw")
             .each(function (key, value) {
-                var url = $(value).attr('data-pdfurl');
-                var inner = $('<div></div>');
+                const url = $(value).attr('data-pdfurl');
+                const inner = $('<div></div>');
                 $(this).append(inner);
                 PDFObject.embed(url, inner, {
                     height: '400px'
@@ -466,12 +472,12 @@ function finishView(view) {
             });
     //syntax highlighting
     view.find("code.raw").removeClass("raw")
-        .each(function (key, value) {
-            var langDiv = $(value);
+        .each((key, value) => {
+            const langDiv = $(value);
             if (langDiv.length > 0) {
-                var reallang = langDiv[0].className.replace(/hljs|wrap/g, '').trim();
-                var codeDiv = langDiv.find('.code');
-                var code = "";
+                const reallang = langDiv[0].className.replace(/hljs|wrap/g, '').trim();
+                const codeDiv = langDiv.find('.code');
+                let code = "";
                 if (codeDiv.length > 0) code = codeDiv.html();
                 else code = langDiv.html();
                 if (!reallang) {
@@ -490,8 +496,8 @@ function finishView(view) {
                     };
                 } else {
                     code = S(code).unescapeHTML().s;
-                    var languages = hljs.listLanguages();
-                    if (languages.indexOf(reallang) == -1) {
+                    const languages = hljs.listLanguages();
+                    if (!languages.includes(reallang)) {
                         var result = hljs.highlightAuto(code);
                     } else {
                         var result = hljs.highlight(reallang, code);
@@ -502,7 +508,7 @@ function finishView(view) {
             }
         });
     //mathjax
-    var mathjaxdivs = view.find('span.mathjax.raw').removeClass("raw").toArray();
+    const mathjaxdivs = view.find('span.mathjax.raw').removeClass("raw").toArray();
     try {
         if (mathjaxdivs.length > 1) {
             MathJax.Hub.Queue(["Typeset", MathJax.Hub, mathjaxdivs]);
@@ -519,16 +525,16 @@ function finishView(view) {
 }
 
 //only static transform should be here
-function postProcess(code) {
-    var result = $('<div>' + code + '</div>');
+export function postProcess(code) {
+    const result = $(`<div>${code}</div>`);
     //link should open in new window or tab
     result.find('a:not([href^="#"]):not([target])').attr('target', '_blank');
 	//update continue line numbers
-	var linenumberdivs = result.find('.gutter.linenumber').toArray();
-	for (var i = 0; i < linenumberdivs.length; i++) {
+	const linenumberdivs = result.find('.gutter.linenumber').toArray();
+	for (let i = 0; i < linenumberdivs.length; i++) {
 		if ($(linenumberdivs[i]).hasClass('continue')) {
-			var startnumber = linenumberdivs[i - 1] ? parseInt($(linenumberdivs[i - 1]).find('> span').last().attr('data-linenumber')) : 0;
-			$(linenumberdivs[i]).find('> span').each(function(key, value) {
+			const startnumber = linenumberdivs[i - 1] ? parseInt($(linenumberdivs[i - 1]).find('> span').last().attr('data-linenumber')) : 0;
+			$(linenumberdivs[i]).find('> span').each((key, value) => {
 				$(value).attr('data-linenumber', startnumber + key + 1);
 			});
 		}
@@ -538,8 +544,8 @@ function postProcess(code) {
 window.postProcess = postProcess;
 
 function generateCleanHTML(view) {
-    var src = view.clone();
-    var eles = src.find('*');
+    const src = view.clone();
+    const eles = src.find('*');
     //remove syncscroll parts
     eles.removeClass('part');
     src.find('*[class=""]').removeAttr('class');
@@ -550,24 +556,24 @@ function generateCleanHTML(view) {
     //disable todo list
     src.find("input.task-list-item-checkbox").attr('disabled', '');
     //replace emoji image path
-    src.find("img.emoji").each(function (key, value) {
-        var name = $(value).attr('alt');
+    src.find("img.emoji").each((key, value) => {
+        let name = $(value).attr('alt');
         name = name.substr(1);
         name = name.slice(0, name.length - 1);
-        $(value).attr('src', 'https://www.tortue.me/emoji/' + name + '.png');
+        $(value).attr('src', `https://www.tortue.me/emoji/${name}.png`);
     });
     //replace video to iframe
-    src.find("div[data-videoid]").each(function (key, value) {
-        var id = $(value).attr('data-videoid');
-        var style = $(value).attr('style');
-        var url = null;
+    src.find("div[data-videoid]").each((key, value) => {
+        const id = $(value).attr('data-videoid');
+        const style = $(value).attr('style');
+        let url = null;
         if ($(value).hasClass('youtube')) {
             url = 'https://www.youtube.com/embed/';
         } else if ($(value).hasClass('vimeo')) {
             url = 'https://player.vimeo.com/video/';
         }
         if (url) {
-            var iframe = $('<iframe frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>');
+            const iframe = $('<iframe frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>');
             iframe.attr('src', url + id);
             iframe.attr('style', style);
             $(value).html(iframe);
@@ -576,45 +582,44 @@ function generateCleanHTML(view) {
     return src;
 }
 
-function exportToRawHTML(view) {
-    var filename = renderFilename(ui.area.markdown) + '.html';
-    var src = generateCleanHTML(view);
+export function exportToRawHTML(view) {
+    const filename = `${renderFilename(ui.area.markdown)}.html`;
+    const src = generateCleanHTML(view);
     $(src).find('a.anchor').remove();
-    var html = src[0].outerHTML;
-    var blob = new Blob([html], {
+    const html = src[0].outerHTML;
+    const blob = new Blob([html], {
         type: "text/html;charset=utf-8"
     });
     saveAs(blob, filename);
 }
 
-var common = require('./common.js');
 //extract markdown body to html and compile to template
-function exportToHTML(view) {
-    var title = renderTitle(ui.area.markdown);
-    var filename = renderFilename(ui.area.markdown) + '.html';
-    var src = generateCleanHTML(view);
+export function exportToHTML(view) {
+    const title = renderTitle(ui.area.markdown);
+    const filename = `${renderFilename(ui.area.markdown)}.html`;
+    const src = generateCleanHTML(view);
     //generate toc
-    var toc = $('#ui-toc').clone();
+    const toc = $('#ui-toc').clone();
     toc.find('*').removeClass('active').find("a[href^='#'][smoothhashscroll]").removeAttr('smoothhashscroll');
-    var tocAffix = $('#ui-toc-affix').clone();
+    const tocAffix = $('#ui-toc-affix').clone();
     tocAffix.find('*').removeClass('active').find("a[href^='#'][smoothhashscroll]").removeAttr('smoothhashscroll');
     //generate html via template
-    $.get(serverurl + '/build/html.min.css', function (css) {
-        $.get(serverurl + '/views/html.hbs', function (data) {
-            var template = Handlebars.compile(data);
-            var context = {
+    $.get(`${serverurl}/build/html.min.css`, css => {
+        $.get(`${serverurl}/views/html.hbs`, data => {
+            const template = Handlebars.compile(data);
+            const context = {
                 url: serverurl,
-                title: title,
-                css: css,
+                title,
+                css,
                 html: src[0].outerHTML,
                 'ui-toc': toc.html(),
                 'ui-toc-affix': tocAffix.html(),
-                lang: (md && md.meta && md.meta.lang) ? 'lang="' + md.meta.lang + '"' : null,
-                dir: (md && md.meta && md.meta.dir) ? 'dir="' + md.meta.dir + '"' : null
+                lang: (md && md.meta && md.meta.lang) ? `lang="${md.meta.lang}"` : null,
+                dir: (md && md.meta && md.meta.dir) ? `dir="${md.meta.dir}"` : null
             };
-            var html = template(context);
+            const html = template(context);
             //        console.log(html);
-            var blob = new Blob([html], {
+            const blob = new Blob([html], {
                 type: "text/html;charset=utf-8"
             });
             saveAs(blob, filename);
@@ -624,17 +629,16 @@ function exportToHTML(view) {
 
 //jQuery sortByDepth
 $.fn.sortByDepth = function () {
-    var ar = this.map(function () {
+    const ar = this.map(function () {
             return {
                 length: $(this).parents().length,
                 elt: this
             }
-        }).get(),
-        result = [],
-        i = ar.length;
-    ar.sort(function (a, b) {
-        return a.length - b.length;
-    });
+        }).get();
+
+    const result = [];
+    let i = ar.length;
+    ar.sort((a, b) => a.length - b.length);
     while (i--) {
         result.push(ar[i].elt);
     }
@@ -642,16 +646,16 @@ $.fn.sortByDepth = function () {
 };
 
 function toggleTodoEvent(e) {
-    var startline = $(this).closest('li').attr('data-startline') - 1;
-    var line = editor.getLine(startline);
-    var matches = line.match(/^[>\s]*[\-\+\*]\s\[([x ])\]/);
+    const startline = $(this).closest('li').attr('data-startline') - 1;
+    const line = editor.getLine(startline);
+    const matches = line.match(/^[>\s]*[\-\+\*]\s\[([x ])\]/);
     if (matches && matches.length >= 2) {
-        var checked = null;
+        let checked = null;
         if (matches[1] == 'x')
             checked = true;
         else if (matches[1] == ' ')
             checked = false;
-        var replacements = matches[0].match(/(^[>\s]*[\-\+\*]\s\[)([x ])(\])/);
+        const replacements = matches[0].match(/(^[>\s]*[\-\+\*]\s\[)([x ])(\])/);
         editor.replaceRange(checked ? ' ' : 'x', {
             line: startline,
             ch: replacements[1].length
@@ -667,11 +671,11 @@ function removeHash() {
     history.pushState("", document.title, window.location.pathname + window.location.search);
 }
 
-var tocExpand = false;
+let tocExpand = false;
 
 function checkExpandToggle() {
-    var toc = $('.ui-toc-dropdown .toc');
-    var toggle = $('.expand-toggle');
+    const toc = $('.ui-toc-dropdown .toc');
+    const toggle = $('.expand-toggle');
     if (!tocExpand) {
         toc.removeClass('expand');
         toggle.text('Expand all');
@@ -682,8 +686,8 @@ function checkExpandToggle() {
 }
 
 //toc
-function generateToc(id) {
-    var target = $('#' + id);
+export function generateToc(id) {
+    const target = $(`#${id}`);
     target.html('');
     new Toc('doc', {
         'level': 3,
@@ -695,25 +699,25 @@ function generateToc(id) {
     });
     if (target.text() == 'undefined')
         target.html('');
-    var tocMenu = $('<div class="toc-menu"></div');
-    var toggle = $('<a class="expand-toggle" href="#">Expand all</a>');
-    var backtotop = $('<a class="back-to-top" href="#">Back to top</a>');
-    var gotobottom = $('<a class="go-to-bottom" href="#">Go to bottom</a>');
+    const tocMenu = $('<div class="toc-menu"></div');
+    const toggle = $('<a class="expand-toggle" href="#">Expand all</a>');
+    const backtotop = $('<a class="back-to-top" href="#">Back to top</a>');
+    const gotobottom = $('<a class="go-to-bottom" href="#">Go to bottom</a>');
     checkExpandToggle();
-    toggle.click(function (e) {
+    toggle.click(e => {
         e.preventDefault();
         e.stopPropagation();
         tocExpand = !tocExpand;
         checkExpandToggle();
     });
-    backtotop.click(function (e) {
+    backtotop.click(e => {
         e.preventDefault();
         e.stopPropagation();
         if (scrollToTop)
             scrollToTop();
         removeHash();
     });
-    gotobottom.click(function (e) {
+    gotobottom.click(e => {
         e.preventDefault();
         e.stopPropagation();
         if (scrollToBottom)
@@ -725,18 +729,18 @@ function generateToc(id) {
 }
 
 //smooth all hash trigger scrolling
-function smoothHashScroll() {
-    var hashElements = $("a[href^='#']:not([smoothhashscroll])").toArray();
-    for (var i = 0; i < hashElements.length; i++) {
-        var element = hashElements[i];
-        var $element = $(element);
-        var hash = element.hash;
+export function smoothHashScroll() {
+    const hashElements = $("a[href^='#']:not([smoothhashscroll])").toArray();
+
+    for (const element of hashElements) {
+        const $element = $(element);
+        const hash = element.hash;
         if (hash) {
             $element.on('click', function (e) {
                 // store hash
-                var hash = decodeURIComponent(this.hash);
+                const hash = decodeURIComponent(this.hash);
                 // escape special characters in jquery selector
-                var $hash = $(hash.replace(/(:|\.|\[|\]|,)/g, "\\$1"));
+                const $hash = $(hash.replace(/(:|\.|\[|\]|,)/g, "\\$1"));
                 // return if no element been selected
                 if ($hash.length <= 0) return;
                 // prevent default anchor click behavior
@@ -744,7 +748,7 @@ function smoothHashScroll() {
                 // animate
                 $('body, html').stop(true, true).animate({
                     scrollTop: $hash.offset().top
-                }, 100, "linear", function () {
+                }, 100, "linear", () => {
                     // when done, add hash to url
                     // (default click behaviour)
                     window.location.hash = hash;
@@ -757,29 +761,29 @@ function smoothHashScroll() {
 
 function imgPlayiframe(element, src) {
     if (!$(element).attr("data-videoid")) return;
-    var iframe = $("<iframe frameborder='0' webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>");
-    $(iframe).attr("src", src + $(element).attr("data-videoid") + '?autoplay=1');
+    const iframe = $("<iframe frameborder='0' webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>");
+    $(iframe).attr("src", `${src + $(element).attr("data-videoid")}?autoplay=1`);
     $(element).find('img').css('visibility', 'hidden');
     $(element).append(iframe);
 }
 
-var anchorForId = function (id) {
-    var anchor = document.createElement("a");
+const anchorForId = id => {
+    const anchor = document.createElement("a");
     anchor.className = "anchor hidden-xs";
-    anchor.href = "#" + id;
+    anchor.href = `#${id}`;
     anchor.innerHTML = "<span class=\"octicon octicon-link\"></span>";
     anchor.title = id;
     return anchor;
 };
 
-var linkifyAnchors = function (level, containingElement) {
-    var headers = containingElement.getElementsByTagName("h" + level);
-    for (var h = 0; h < headers.length; h++) {
-        var header = headers[h];
+const linkifyAnchors = (level, containingElement) => {
+    const headers = containingElement.getElementsByTagName(`h${level}`);
+
+    for (const header of headers) {
         if (header.getElementsByClassName("anchor").length == 0) {
             if (typeof header.id == "undefined" || header.id == "") {
                 //to escape characters not allow in css and humanize
-                var id = slugifyWithUTF8(getHeaderContent(header));
+                const id = slugifyWithUTF8(getHeaderContent(header));
                 header.id = id;
             }
             header.insertBefore(anchorForId(header.id), header.firstChild);
@@ -787,49 +791,49 @@ var linkifyAnchors = function (level, containingElement) {
     }
 };
 
-function autoLinkify(view) {
-    var contentBlock = view[0];
+export function autoLinkify(view) {
+    const contentBlock = view[0];
     if (!contentBlock) {
         return;
     }
-    for (var level = 1; level <= 6; level++) {
+    for (let level = 1; level <= 6; level++) {
         linkifyAnchors(level, contentBlock);
     }
 }
 
 function getHeaderContent(header) {
-    var headerHTML = $(header).clone();
+    const headerHTML = $(header).clone();
     headerHTML.find('.MathJax_Preview').remove();
     headerHTML.find('.MathJax').remove();
     return headerHTML[0].innerHTML;
 }
 
-function deduplicatedHeaderId(view) {
-    var headers = view.find(':header.raw').removeClass('raw').toArray();
-    for (var i = 0; i < headers.length; i++) {
-        var id = $(headers[i]).attr('id');
+export function deduplicatedHeaderId(view) {
+    const headers = view.find(':header.raw').removeClass('raw').toArray();
+    for (let i = 0; i < headers.length; i++) {
+        const id = $(headers[i]).attr('id');
         if (!id) continue;
-        var duplicatedHeaders = view.find(':header[id="' + id + '"]').toArray();
-        for (var j = 0; j < duplicatedHeaders.length; j++) {
+        const duplicatedHeaders = view.find(`:header[id="${id}"]`).toArray();
+        for (let j = 0; j < duplicatedHeaders.length; j++) {
             if (duplicatedHeaders[j] != headers[i]) {
-                var newId = id + j;
-                var $duplicatedHeader = $(duplicatedHeaders[j]);
+                const newId = id + j;
+                const $duplicatedHeader = $(duplicatedHeaders[j]);
                 $duplicatedHeader.attr('id', newId);
-                var $headerLink = $duplicatedHeader.find('> .header-link');
-                $headerLink.attr('href', '#' + newId);
+                const $headerLink = $duplicatedHeader.find('> .header-link');
+                $headerLink.attr('href', `#${newId}`);
                 $headerLink.attr('title', newId);
             }
         }
     }
 }
 
-function renderTOC(view) {
-    var tocs = view.find('.toc').toArray();
-	for (var i = 0; i < tocs.length; i++) {
-        var toc = $(tocs[i]);
-        var id = 'toc' + i;
+export function renderTOC(view) {
+    const tocs = view.find('.toc').toArray();
+	for (let i = 0; i < tocs.length; i++) {
+        const toc = $(tocs[i]);
+        const id = `toc${i}`;
         toc.attr('id', id);
-        var target = $('#' + id);
+        const target = $(`#${id}`);
         target.html('');
         new Toc('doc', {
             'level': 3,
@@ -844,8 +848,8 @@ function renderTOC(view) {
     }
 }
 
-function scrollToHash() {
-    var hash = location.hash;
+export function scrollToHash() {
+    const hash = location.hash;
     location.hash = "";
     location.hash = hash;
 }
@@ -855,39 +859,39 @@ function highlightRender(code, lang) {
         return;
     code = S(code).escapeHTML().s
     if (lang == 'sequence') {
-        return '<div class="sequence-diagram raw">' + code + '</div>';
+        return `<div class="sequence-diagram raw">${code}</div>`;
     } else if (lang == 'flow') {
-        return '<div class="flow-chart raw">' + code + '</div>';
+        return `<div class="flow-chart raw">${code}</div>`;
     } else if (lang == 'graphviz') {
-        return '<div class="graphviz raw">' + code + '</div>';
+        return `<div class="graphviz raw">${code}</div>`;
     } else if (lang == 'mermaid') {
-        return '<div class="mermaid raw">' + code + '</div>';
+        return `<div class="mermaid raw">${code}</div>`;
     }
-    var result = {
+    const result = {
         value: code
     };
-	var showlinenumbers = /\=$|\=\d+$|\=\+$/.test(lang);
+	const showlinenumbers = /\=$|\=\d+$|\=\+$/.test(lang);
     if (showlinenumbers) {
-		var startnumber = 1;
-		var matches = lang.match(/\=(\d+)$/);
+		let startnumber = 1;
+		const matches = lang.match(/\=(\d+)$/);
 		if (matches)
 			startnumber = parseInt(matches[1]);
-        var lines = result.value.split('\n');
-        var linenumbers = [];
-        for (var i = 0; i < lines.length - 1; i++) {
-            linenumbers[i] = "<span data-linenumber='" + (startnumber + i) + "'></span>";
+        const lines = result.value.split('\n');
+        const linenumbers = [];
+        for (let i = 0; i < lines.length - 1; i++) {
+            linenumbers[i] = `<span data-linenumber='${startnumber + i}'></span>`;
         }
-		var continuelinenumber = /\=\+$/.test(lang);
-        var linegutter = "<div class='gutter linenumber" + (continuelinenumber ? " continue" : "") + "'>" + linenumbers.join('\n') + "</div>";
-        result.value = "<div class='wrapper'>" + linegutter + "<div class='code'>" + result.value + "</div></div>";
+		const continuelinenumber = /\=\+$/.test(lang);
+        const linegutter = `<div class='gutter linenumber${continuelinenumber ? " continue" : ""}'>${linenumbers.join('\n')}</div>`;
+        result.value = `<div class='wrapper'>${linegutter}<div class='code'>${result.value}</div></div>`;
     }
     return result.value;
 }
 
-var markdownit = require('markdown-it');
-var markdownitContainer = require('markdown-it-container');
+import markdownit from 'markdown-it';
+import markdownitContainer from 'markdown-it-container';
 
-var md = markdownit('default', {
+export let md = markdownit('default', {
     html: true,
     breaks: true,
     langPrefix: "",
@@ -923,19 +927,17 @@ emojify.setConfig({
         elements: ['script', 'textarea', 'a', 'pre', 'code', 'svg'],
         classes: ['no-emojify']
     },
-    img_dir: serverurl + '/build/emojify.js/dist/images/basic',
+    img_dir: `${serverurl}/build/emojify.js/dist/images/basic`,
     ignore_emoticons: true
 });
 
-md.renderer.rules.emoji = function(token, idx) {
-    return emojify.replace(':' + token[idx].markup + ':');
-};
+md.renderer.rules.emoji = (token, idx) => emojify.replace(`:${token[idx].markup}:`);
 
 function renderContainer(tokens, idx, options, env, self) {
     tokens[idx].attrJoin('role', 'alert');
     tokens[idx].attrJoin('class', 'alert');
-    tokens[idx].attrJoin('class', 'alert-' + tokens[idx].info.trim());
-    return self.renderToken.apply(self, arguments);
+    tokens[idx].attrJoin('class', `alert-${tokens[idx].info.trim()}`);
+    return self.renderToken(...arguments);
 }
 md.use(markdownitContainer, 'success', { render: renderContainer });
 md.use(markdownitContainer, 'info', { render: renderContainer });
@@ -944,25 +946,25 @@ md.use(markdownitContainer, 'danger', { render: renderContainer });
 
 md.renderer.rules.image = function (tokens, idx, options, env, self) {
     tokens[idx].attrJoin('class', 'raw');
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.list_item_open = function (tokens, idx, options, env, self) {
     tokens[idx].attrJoin('class', 'raw');
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.blockquote_open = function (tokens, idx, options, env, self) {
     tokens[idx].attrJoin('class', 'raw');
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.heading_open = function (tokens, idx, options, env, self) {
     tokens[idx].attrJoin('class', 'raw');
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
-md.renderer.rules.fence = function (tokens, idx, options, env, self) {
-    var token = tokens[idx],
-      info = token.info ? md.utils.unescapeAll(token.info).trim() : '',
-      langName = '',
-      highlighted;
+md.renderer.rules.fence = (tokens, idx, options, env, self) => {
+    const token = tokens[idx];
+    const info = token.info ? md.utils.unescapeAll(token.info).trim() : '';
+    let langName = '';
+    let highlighted;
 
     if (info) {
         langName = info.split(/\s+/g)[0];
@@ -979,110 +981,99 @@ md.renderer.rules.fence = function (tokens, idx, options, env, self) {
     }
 
     if (highlighted.indexOf('<pre') === 0) {
-        return highlighted + '\n';
+        return `${highlighted}\n`;
     }
 
-    return  '<pre><code' + self.renderAttrs(token) + '>'
-        + highlighted
-        + '</code></pre>\n';
+    return  `<pre><code${self.renderAttrs(token)}>${highlighted}</code></pre>\n`;
 };
 
 /* Defined regex markdown it plugins */
-var Plugin = require('markdown-it-regexp');
+import Plugin from 'markdown-it-regexp';
 
 //youtube
-var youtubePlugin = new Plugin(
+const youtubePlugin = new Plugin(
     // regexp to match
     /{%youtube\s*([\d\D]*?)\s*%}/,
 
-    // this function will be called when something matches
-    function (match, utils) {
-        var videoid = match[1];
+    (match, utils) => {
+        const videoid = match[1];
         if (!videoid) return;
-        var div = $('<div class="youtube raw"></div>');
+        const div = $('<div class="youtube raw"></div>');
         div.attr('data-videoid', videoid);
-        var thumbnail_src = '//img.youtube.com/vi/' + videoid + '/hqdefault.jpg';
-        var image = '<img src="' + thumbnail_src + '" />';
+        const thumbnail_src = `//img.youtube.com/vi/${videoid}/hqdefault.jpg`;
+        const image = `<img src="${thumbnail_src}" />`;
         div.append(image);
-        var icon = '<i class="icon fa fa-youtube-play fa-5x"></i>';
+        const icon = '<i class="icon fa fa-youtube-play fa-5x"></i>';
         div.append(icon);
         return div[0].outerHTML;
     }
 );
 //vimeo
-var vimeoPlugin = new Plugin(
+const vimeoPlugin = new Plugin(
     // regexp to match
     /{%vimeo\s*([\d\D]*?)\s*%}/,
 
-    // this function will be called when something matches
-    function (match, utils) {
-        var videoid = match[1];
+    (match, utils) => {
+        const videoid = match[1];
         if (!videoid) return;
-        var div = $('<div class="vimeo raw"></div>');
+        const div = $('<div class="vimeo raw"></div>');
         div.attr('data-videoid', videoid);
-        var icon = '<i class="icon fa fa-vimeo-square fa-5x"></i>';
+        const icon = '<i class="icon fa fa-vimeo-square fa-5x"></i>';
         div.append(icon);
         return div[0].outerHTML;
     }
 );
 //gist
-var gistPlugin = new Plugin(
+const gistPlugin = new Plugin(
     // regexp to match
     /{%gist\s*([\d\D]*?)\s*%}/,
 
-    // this function will be called when something matches
-    function (match, utils) {
-        var gistid = match[1];
-        var code = '<code data-gist-id="' + gistid + '"/>';
+    (match, utils) => {
+        const gistid = match[1];
+        const code = `<code data-gist-id="${gistid}"/>`;
         return code;
     }
 );
 //TOC
-var tocPlugin = new Plugin(
+const tocPlugin = new Plugin(
     // regexp to match
     /^\[TOC\]$/i,
 
-    // this function will be called when something matches
-    function (match, utils) {
-        return '<div class="toc"></div>';
-    }
+    (match, utils) => '<div class="toc"></div>'
 );
 //slideshare
-var slidesharePlugin = new Plugin(
+const slidesharePlugin = new Plugin(
     // regexp to match
     /{%slideshare\s*([\d\D]*?)\s*%}/,
 
-    // this function will be called when something matches
-    function (match, utils) {
-        var slideshareid = match[1];
-        var div = $('<div class="slideshare raw"></div>');
+    (match, utils) => {
+        const slideshareid = match[1];
+        const div = $('<div class="slideshare raw"></div>');
         div.attr('data-slideshareid', slideshareid);
         return div[0].outerHTML;
     }
 );
 //speakerdeck
-var speakerdeckPlugin = new Plugin(
+const speakerdeckPlugin = new Plugin(
     // regexp to match
     /{%speakerdeck\s*([\d\D]*?)\s*%}/,
 
-    // this function will be called when something matches
-    function (match, utils) {
-        var speakerdeckid = match[1];
-        var div = $('<div class="speakerdeck raw"></div>');
+    (match, utils) => {
+        const speakerdeckid = match[1];
+        const div = $('<div class="speakerdeck raw"></div>');
         div.attr('data-speakerdeckid', speakerdeckid);
         return div[0].outerHTML;
     }
 );
 //pdf
-var pdfPlugin = new Plugin(
+const pdfPlugin = new Plugin(
     // regexp to match
     /{%pdf\s*([\d\D]*?)\s*%}/,
 
-    // this function will be called when something matches
-    function (match, utils) {
-        var pdfurl = match[1];
+    (match, utils) => {
+        const pdfurl = match[1];
         if (!isValidURL(pdfurl)) return match[0];
-        var div = $('<div class="pdf raw"></div>');
+        const div = $('<div class="pdf raw"></div>');
         div.attr('data-pdfurl', pdfurl);
         return div[0].outerHTML;
     }
@@ -1090,8 +1081,8 @@ var pdfPlugin = new Plugin(
 
 //yaml meta, from https://github.com/eugeneware/remarkable-meta
 function get(state, line) {
-    var pos = state.bMarks[line];
-    var max = state.eMarks[line];
+    const pos = state.bMarks[line];
+    const max = state.eMarks[line];
     return state.src.substr(pos, max - pos);
 }
 
@@ -1100,9 +1091,9 @@ function meta(state, start, end, silent) {
     if (state.tShift[start] < 0) return false;
     if (!get(state, start).match(/^---$/)) return false;
 
-    var data = [];
+    const data = [];
     for (var line = start + 1; line < end; line++) {
-        var str = get(state, line);
+        const str = get(state, line);
         if (str.match(/^(\.{3}|-{3})$/)) break;
         if (state.tShift[line] < 0) break;
         data.push(str);
@@ -1138,24 +1129,6 @@ md.use(slidesharePlugin);
 md.use(speakerdeckPlugin);
 md.use(pdfPlugin);
 
-module.exports = {
-  md: md,
-  updateLastChange: updateLastChange,
-  postProcess: postProcess,
-  finishView: finishView,
-  autoLinkify: autoLinkify,
-  deduplicatedHeaderId: deduplicatedHeaderId,
-  renderTOC: renderTOC,
-  renderTitle: renderTitle,
-  renderFilename: renderFilename,
-  renderTags: renderTags,
-  isValidURL: isValidURL,
-  generateToc: generateToc,
-  smoothHashScroll: smoothHashScroll,
-  scrollToHash: scrollToHash,
-  updateLastChangeUser: updateLastChangeUser,
-  updateOwner: updateOwner,
-  parseMeta: parseMeta,
-  exportToHTML: exportToHTML,
-  exportToRawHTML: exportToRawHTML
+export default {
+  md
 };
diff --git a/public/js/history.js b/public/js/history.js
index 6972f24..f120168 100644
--- a/public/js/history.js
+++ b/public/js/history.js
@@ -1,10 +1,9 @@
-var store = require('store');
-var S = require('string');
-
-var common = require('./common');
-var checkIfAuth = common.checkIfAuth;
-var urlpath = common.urlpath;
-var getLoginState = common.getLoginState;
+import store from 'store';
+import S from 'string';
+import {
+    checkIfAuth,
+    urlpath
+} from './common';
 
 window.migrateHistoryFromTempCallback = null;
 
@@ -12,22 +11,22 @@ migrateHistoryFromTemp();
 
 function migrateHistoryFromTemp() {
     if (url('#tempid')) {
-        $.get(serverurl + '/temp', {
+        $.get(`${serverurl}/temp`, {
                 tempid: url('#tempid')
             })
-            .done(function (data) {
+            .done(data => {
                 if (data && data.temp) {
-                    getStorageHistory(function (olddata) {
+                    getStorageHistory(olddata => {
                         if (!olddata || olddata.length == 0) {
                             saveHistoryToStorage(JSON.parse(data.temp));
                         }
                     });
                 }
             })
-            .always(function () {
-                var hash = location.hash.split('#')[1];
+            .always(() => {
+                let hash = location.hash.split('#')[1];
                 hash = hash.split('&');
-                for (var i = 0; i < hash.length; i++)
+                for (let i = 0; i < hash.length; i++)
                     if (hash[i].indexOf('tempid') == 0) {
                         hash.splice(i, 1);
                         i--;
@@ -40,12 +39,12 @@ function migrateHistoryFromTemp() {
     }
 }
 
-function saveHistory(notehistory) {
+export function saveHistory(notehistory) {
     checkIfAuth(
-        function () {
+        () => {
             saveHistoryToServer(notehistory);
         },
-        function () {
+        () => {
             saveHistoryToStorage(notehistory);
         }
     );
@@ -65,7 +64,7 @@ function saveHistoryToCookie(notehistory) {
 }
 
 function saveHistoryToServer(notehistory) {
-    $.post(serverurl + '/history', {
+    $.post(`${serverurl}/history`, {
         history: JSON.stringify(notehistory)
     });
 }
@@ -75,37 +74,37 @@ function saveCookieHistoryToStorage(callback) {
     callback();
 }
 
-function saveStorageHistoryToServer(callback) {
-    var data = store.get('notehistory');
+export function saveStorageHistoryToServer(callback) {
+    const data = store.get('notehistory');
     if (data) {
-        $.post(serverurl + '/history', {
+        $.post(`${serverurl}/history`, {
                 history: data
             })
-            .done(function (data) {
+            .done(data => {
                 callback(data);
             });
     }
 }
 
 function saveCookieHistoryToServer(callback) {
-    $.post(serverurl + '/history', {
+    $.post(`${serverurl}/history`, {
             history: Cookies.get('notehistory')
         })
-        .done(function (data) {
+        .done(data => {
             callback(data);
         });
 }
 
-function clearDuplicatedHistory(notehistory) {
-    var newnotehistory = [];
-    for (var i = 0; i < notehistory.length; i++) {
-        var found = false;
-        for (var j = 0; j < newnotehistory.length; j++) {
-            var id = notehistory[i].id.replace(/\=+$/, '');
-            var newId = newnotehistory[j].id.replace(/\=+$/, '');
+export function clearDuplicatedHistory(notehistory) {
+    const newnotehistory = [];
+    for (let i = 0; i < notehistory.length; i++) {
+        let found = false;
+        for (let j = 0; j < newnotehistory.length; j++) {
+            const id = notehistory[i].id.replace(/\=+$/, '');
+            const newId = newnotehistory[j].id.replace(/\=+$/, '');
             if (id == newId || notehistory[i].id == newnotehistory[j].id || !notehistory[i].id || !newnotehistory[j].id) {
-                var time = (typeof notehistory[i].time === 'number' ? moment(notehistory[i].time) : moment(notehistory[i].time, 'MMMM Do YYYY, h:mm:ss a'));
-                var newTime = (typeof newnotehistory[i].time === 'number' ? moment(newnotehistory[i].time) : moment(newnotehistory[i].time, 'MMMM Do YYYY, h:mm:ss a'));
+                const time = (typeof notehistory[i].time === 'number' ? moment(notehistory[i].time) : moment(notehistory[i].time, 'MMMM Do YYYY, h:mm:ss a'));
+                const newTime = (typeof newnotehistory[i].time === 'number' ? moment(newnotehistory[i].time) : moment(newnotehistory[i].time, 'MMMM Do YYYY, h:mm:ss a'));
                 if(time >= newTime) {
                     newnotehistory[j] = notehistory[i];
                 }
@@ -123,42 +122,42 @@ function addHistory(id, text, time, tags, pinned, notehistory) {
     // only add when note id exists
     if (id) {
       notehistory.push({
-          id: id,
-          text: text,
-          time: time,
-          tags: tags,
-          pinned: pinned
+          id,
+          text,
+          time,
+          tags,
+          pinned
       });
     }
     return notehistory;
 }
 
-function removeHistory(id, notehistory) {
-    for (var i = 0; i < notehistory.length; i++) {
+export function removeHistory(id, notehistory) {
+    for (let i = 0; i < notehistory.length; i++) {
         if (notehistory[i].id == id) {
             notehistory.splice(i, 1);
-			i--;
-		}
+            i -= 1;
+        }
     }
     return notehistory;
 }
 
 //used for inner
-function writeHistory(title, tags) {
+export function writeHistory(title, tags) {
     checkIfAuth(
-        function () {
+        () => {
             // no need to do this anymore, this will count from server-side
             // writeHistoryToServer(title, tags);
         },
-        function () {
+        () => {
             writeHistoryToStorage(title, tags);
         }
     );
 }
 
 function writeHistoryToServer(title, tags) {
-    $.get(serverurl + '/history')
-        .done(function (data) {
+    $.get(`${serverurl}/history`)
+        .done(data => {
             try {
                 if (data.history) {
                     var notehistory = data.history;
@@ -171,10 +170,10 @@ function writeHistoryToServer(title, tags) {
             if (!notehistory)
                 notehistory = [];
 
-            var newnotehistory = generateHistory(title, tags, notehistory);
+            const newnotehistory = generateHistory(title, tags, notehistory);
             saveHistoryToServer(newnotehistory);
         })
-        .fail(function (xhr, status, error) {
+        .fail((xhr, status, error) => {
             console.error(xhr.responseText);
         });
 }
@@ -188,13 +187,13 @@ function writeHistoryToCookie(title, tags) {
     if (!notehistory)
         notehistory = [];
 
-    var newnotehistory = generateHistory(title, tags, notehistory);
+    const newnotehistory = generateHistory(title, tags, notehistory);
     saveHistoryToCookie(newnotehistory);
 }
 
 function writeHistoryToStorage(title, tags) {
     if (store.enabled) {
-        var data = store.get('notehistory');
+        let data = store.get('notehistory');
         if (data) {
             if (typeof data == "string")
                 data = JSON.parse(data);
@@ -204,7 +203,7 @@ function writeHistoryToStorage(title, tags) {
         if (!notehistory)
             notehistory = [];
 
-        var newnotehistory = generateHistory(title, tags, notehistory);
+        const newnotehistory = generateHistory(title, tags, notehistory);
         saveHistoryToStorage(newnotehistory);
     } else {
         writeHistoryToCookie(title, tags);
@@ -212,32 +211,30 @@ function writeHistoryToStorage(title, tags) {
 }
 
 if (!Array.isArray) {
-    Array.isArray = function(arg) {
-        return Object.prototype.toString.call(arg) === '[object Array]';
-    };
+    Array.isArray = arg => Object.prototype.toString.call(arg) === '[object Array]';
 }
 
 function renderHistory(title, tags) {
     //console.debug(tags);
-    var id = urlpath ? location.pathname.slice(urlpath.length + 1, location.pathname.length).split('/')[1] : location.pathname.split('/')[1];
+    const id = urlpath ? location.pathname.slice(urlpath.length + 1, location.pathname.length).split('/')[1] : location.pathname.split('/')[1];
     return {
-        id: id,
+        id,
         text: title,
         time: moment().valueOf(),
-        tags: tags
+        tags
     };
 }
 
 function generateHistory(title, tags, notehistory) {
-    var info = renderHistory(title, tags);
-	//keep any pinned data
-	var pinned = false;
-	for (var i = 0; i < notehistory.length; i++) {
-		if (notehistory[i].id == info.id && notehistory[i].pinned) {
-			pinned = true;
-			break;
-		}
-	}
+    const info = renderHistory(title, tags);
+    //keep any pinned data
+    let pinned = false;
+    for (let i = 0; i < notehistory.length; i++) {
+        if (notehistory[i].id == info.id && notehistory[i].pinned) {
+            pinned = true;
+            break;
+        }
+    }
     notehistory = removeHistory(info.id, notehistory);
     notehistory = addHistory(info.id, info.text, info.time, info.tags, pinned, notehistory);
     notehistory = clearDuplicatedHistory(notehistory);
@@ -245,25 +242,25 @@ function generateHistory(title, tags, notehistory) {
 }
 
 //used for outer
-function getHistory(callback) {
+export function getHistory(callback) {
     checkIfAuth(
-        function () {
+        () => {
             getServerHistory(callback);
         },
-        function () {
+        () => {
             getStorageHistory(callback);
         }
     );
 }
 
 function getServerHistory(callback) {
-    $.get(serverurl + '/history')
-        .done(function (data) {
+    $.get(`${serverurl}/history`)
+        .done(data => {
             if (data.history) {
                 callback(data.history);
             }
         })
-        .fail(function (xhr, status, error) {
+        .fail((xhr, status, error) => {
             console.error(xhr.responseText);
         });
 }
@@ -272,9 +269,9 @@ function getCookieHistory(callback) {
     callback(Cookies.getJSON('notehistory'));
 }
 
-function getStorageHistory(callback) {
+export function getStorageHistory(callback) {
     if (store.enabled) {
-        var data = store.get('notehistory');
+        let data = store.get('notehistory');
         if (data) {
             if (typeof data == "string")
                 data = JSON.parse(data);
@@ -286,37 +283,37 @@ function getStorageHistory(callback) {
     }
 }
 
-function parseHistory(list, callback) {
+export function parseHistory(list, callback) {
     checkIfAuth(
-        function () {
+        () => {
             parseServerToHistory(list, callback);
         },
-        function () {
+        () => {
             parseStorageToHistory(list, callback);
         }
     );
 }
 
-function parseServerToHistory(list, callback) {
-    $.get(serverurl + '/history')
-        .done(function (data) {
+export function parseServerToHistory(list, callback) {
+    $.get(`${serverurl}/history`)
+        .done(data => {
             if (data.history) {
                 parseToHistory(list, data.history, callback);
             }
         })
-        .fail(function (xhr, status, error) {
+        .fail((xhr, status, error) => {
             console.error(xhr.responseText);
         });
 }
 
 function parseCookieToHistory(list, callback) {
-    var notehistory = Cookies.getJSON('notehistory');
+    const notehistory = Cookies.getJSON('notehistory');
     parseToHistory(list, notehistory, callback);
 }
 
-function parseStorageToHistory(list, callback) {
+export function parseStorageToHistory(list, callback) {
     if (store.enabled) {
-        var data = store.get('notehistory');
+        let data = store.get('notehistory');
         if (data) {
             if (typeof data == "string")
                 data = JSON.parse(data);
@@ -332,9 +329,9 @@ function parseToHistory(list, notehistory, callback) {
     if (!callback) return;
     else if (!list || !notehistory) callback(list, notehistory);
     else if (notehistory && notehistory.length > 0) {
-        for (var i = 0; i < notehistory.length; i++) {
+        for (let i = 0; i < notehistory.length; i++) {
             //parse time to timestamp and fromNow
-            var timestamp = (typeof notehistory[i].time === 'number' ? moment(notehistory[i].time) : moment(notehistory[i].time, 'MMMM Do YYYY, h:mm:ss a'));
+            const timestamp = (typeof notehistory[i].time === 'number' ? moment(notehistory[i].time) : moment(notehistory[i].time, 'MMMM Do YYYY, h:mm:ss a'));
             notehistory[i].timestamp = timestamp.valueOf();
             notehistory[i].fromNow = timestamp.fromNow();
             notehistory[i].time = timestamp.format('llll');
@@ -349,42 +346,23 @@ function parseToHistory(list, notehistory, callback) {
     callback(list, notehistory);
 }
 
-function postHistoryToServer(noteId, data, callback) {
-    $.post(serverurl + '/history/' + noteId, data)
-    .done(function (result) {
-        return callback(null, result);
-    })
-    .fail(function (xhr, status, error) {
+export function postHistoryToServer(noteId, data, callback) {
+    $.post(`${serverurl}/history/${noteId}`, data)
+    .done(result => callback(null, result))
+    .fail((xhr, status, error) => {
         console.error(xhr.responseText);
         return callback(error, null);
     });
 }
 
-function deleteServerHistory(noteId, callback) {
+export function deleteServerHistory(noteId, callback) {
     $.ajax({
-        url: serverurl + '/history' + (noteId ? '/' + noteId : ""),
+        url: `${serverurl}/history${noteId ? '/' + noteId : ""}`,
         type: 'DELETE'
     })
-    .done(function (result) {
-        return callback(null, result);
-    })
-    .fail(function (xhr, status, error) {
+    .done(result => callback(null, result))
+    .fail((xhr, status, error) => {
         console.error(xhr.responseText);
         return callback(error, null);
     });
 }
-
-module.exports = {
-    writeHistory: writeHistory,
-    parseHistory: parseHistory,
-    getStorageHistory: getStorageHistory,
-    getHistory: getHistory,
-    saveHistory: saveHistory,
-    removeHistory: removeHistory,
-    parseStorageToHistory: parseStorageToHistory,
-    postHistoryToServer: postHistoryToServer,
-    deleteServerHistory: deleteServerHistory,
-    parseServerToHistory: parseServerToHistory,
-    saveStorageHistoryToServer: saveStorageHistoryToServer,
-    clearDuplicatedHistory: clearDuplicatedHistory
-}
diff --git a/public/js/index.js b/public/js/index.js
index 8921eda..660f73e 100644
--- a/public/js/index.js
+++ b/public/js/index.js
@@ -17,52 +17,55 @@ var _ = require("lodash");
 
 var List = require('list.js');
 
-var common = require('./common.js');
-var urlpath = common.urlpath;
-var noteid = common.noteid;
-var debug = common.debug;
-var version = common.version;
-var GOOGLE_API_KEY = common.GOOGLE_API_KEY;
-var GOOGLE_CLIENT_ID = common.GOOGLE_CLIENT_ID;
-var DROPBOX_APP_KEY = common.DROPBOX_APP_KEY;
-var noteurl = common.noteurl;
+import {
+    checkLoginStateChanged,
+    setloginStateChangeEvent,
+    debug,
+    DROPBOX_APP_KEY,
+    GOOGLE_API_KEY,
+    GOOGLE_CLIENT_ID,
+    noteid,
+    noteurl,
+    urlpath,
+    version
+} from './common';
 
-var checkLoginStateChanged = common.checkLoginStateChanged;
-var loginStateChangeEvent = common.loginStateChangeEvent;
+import {
+    autoLinkify,
+    deduplicatedHeaderId,
+    exportToHTML,
+    exportToRawHTML,
+    finishView,
+    generateToc,
+    isValidURL,
+    md,
+    parseMeta,
+    postProcess,
+    renderFilename,
+    renderTOC,
+    renderTags,
+    renderTitle,
+    scrollToHash,
+    smoothHashScroll,
+    updateLastChange,
+    updateLastChangeUser,
+    updateOwner
+} from './extra';
 
-var extra = require('./extra');
-var md = extra.md;
-var updateLastChange = extra.updateLastChange;
-var postProcess = extra.postProcess;
-var finishView = extra.finishView;
-var autoLinkify = extra.autoLinkify;
-var generateToc = extra.generateToc;
-var smoothHashScroll = extra.smoothHashScroll;
-var deduplicatedHeaderId = extra.deduplicatedHeaderId;
-var renderTOC = extra.renderTOC;
-var renderTitle = extra.renderTitle;
-var renderFilename = extra.renderFilename;
-var renderTags = extra.renderTags;
-var isValidURL = extra.isValidURL;
-var scrollToHash = extra.scrollToHash;
-var updateLastChangeUser = extra.updateLastChangeUser;
-var updateOwner = extra.updateOwner;
-var parseMeta = extra.parseMeta;
-var exportToHTML = extra.exportToHTML;
-var exportToRawHTML = extra.exportToRawHTML;
+import {
+    clearMap,
+    setupSyncAreas,
+    syncScrollToEdit,
+    syncScrollToView
+} from './syncscroll';
 
-var syncScroll = require('./syncscroll');
-var setupSyncAreas = syncScroll.setupSyncAreas;
-var clearMap = syncScroll.clearMap;
-var syncScrollToEdit = syncScroll.syncScrollToEdit;
-var syncScrollToView = syncScroll.syncScrollToView;
-
-var historyModule = require('./history');
-var writeHistory = historyModule.writeHistory;
-var deleteServerHistory = historyModule.deleteServerHistory;
-var getHistory = historyModule.getHistory;
-var saveHistory = historyModule.saveHistory;
-var removeHistory = historyModule.removeHistory;
+import {
+    writeHistory,
+    deleteServerHistory,
+    getHistory,
+    saveHistory,
+    removeHistory
+} from './history';
 
 var renderer = require('./render');
 var preventXSS = renderer.preventXSS;
@@ -962,10 +965,10 @@ function setNeedRefresh() {
     showStatus(statusType.offline);
 }
 
-loginStateChangeEvent = function () {
+setloginStateChangeEvent(function () {
     setRefreshModal('user-state-changed');
     setNeedRefresh();
-};
+});
 
 //visibility
 var wasFocus = false;
@@ -3693,6 +3696,7 @@ function checkCursorMenuInner() {
     var offsetLeft = 0;
     var offsetTop = defaultTextHeight;
     // set up side down
+    window.upSideDown = false;
     var lastUpSideDown = upSideDown = false;
     // only do when have width and height
     if (width > 0 && height > 0) {
diff --git a/public/js/pretty.js b/public/js/pretty.js
index c1a471a..64d41c4 100644
--- a/public/js/pretty.js
+++ b/public/js/pretty.js
@@ -4,31 +4,33 @@ require('../css/site.css');
 
 require('highlight.js/styles/github-gist.css');
 
-var extra = require('./extra');
-var md = extra.md;
-var finishView = extra.finishView;
-var autoLinkify = extra.autoLinkify;
-var deduplicatedHeaderId = extra.deduplicatedHeaderId;
-var renderTOC = extra.renderTOC;
-var generateToc = extra.generateToc;
-var smoothHashScroll = extra.smoothHashScroll;
-var postProcess = extra.postProcess;
-var updateLastChange = extra.updateLastChange;
-var parseMeta = extra.parseMeta;
-var scrollToHash = extra.scrollToHash;
-var preventXSS = require('./render').preventXSS;
+import {
+    autoLinkify,
+    deduplicatedHeaderId,
+    finishView,
+    generateToc,
+    md,
+    parseMeta,
+    postProcess,
+    renderTOC,
+    scrollToHash,
+    smoothHashScroll,
+    updateLastChange
+} from './extra';
 
-var markdown = $("#doc.markdown-body");
-var text = markdown.text();
-var lastMeta = md.meta;
+import { preventXSS } from './render';
+
+const markdown = $("#doc.markdown-body");
+const text = markdown.text();
+const lastMeta = md.meta;
 md.meta = {};
-var rendered = md.render(text);
+let rendered = md.render(text);
 if (md.meta.type && md.meta.type === 'slide') {
-    var slideOptions = {
+    const slideOptions = {
         separator: '^(\r\n?|\n)---(\r\n?|\n)$',
         verticalSeparator: '^(\r\n?|\n)----(\r\n?|\n)$'
     };
-    var slides = RevealMarkdown.slidify(text, slideOptions);
+    const slides = RevealMarkdown.slidify(text, slideOptions);
     markdown.html(slides);
     RevealMarkdown.initialize();
     // prevent XSS
@@ -46,10 +48,11 @@ if (md.meta.type && md.meta.type === 'slide') {
     }
     // prevent XSS
     rendered = preventXSS(rendered);
-    var result = postProcess(rendered);
+    const result = postProcess(rendered);
     markdown.html(result.html());
 }
 $(document.body).show();
+
 finishView(markdown);
 autoLinkify(markdown);
 deduplicatedHeaderId(markdown);
@@ -60,17 +63,18 @@ smoothHashScroll();
 createtime = lastchangeui.time.attr('data-createtime');
 lastchangetime = lastchangeui.time.attr('data-updatetime');
 updateLastChange();
-var url = window.location.pathname;
-$('.ui-edit').attr('href', url + '/edit');
-var toc = $('.ui-toc');
-var tocAffix = $('.ui-affix-toc');
-var tocDropdown = $('.ui-toc-dropdown');
+
+const url = window.location.pathname;
+$('.ui-edit').attr('href', `${url}/edit`);
+const toc = $('.ui-toc');
+const tocAffix = $('.ui-affix-toc');
+const tocDropdown = $('.ui-toc-dropdown');
 //toc
-tocDropdown.click(function (e) {
+tocDropdown.click(e => {
     e.stopPropagation();
 });
 
-var enoughForAffixToc = true;
+let enoughForAffixToc = true;
 
 function generateScrollspy() {
     $(document.body).scrollspy({
@@ -89,18 +93,18 @@ function generateScrollspy() {
 
 function windowResize() {
     //toc right
-    var paddingRight = parseFloat(markdown.css('padding-right'));
-    var right = ($(window).width() - (markdown.offset().left + markdown.outerWidth() - paddingRight));
-    toc.css('right', right + 'px');
+    const paddingRight = parseFloat(markdown.css('padding-right'));
+    const right = ($(window).width() - (markdown.offset().left + markdown.outerWidth() - paddingRight));
+    toc.css('right', `${right}px`);
     //affix toc left
-    var newbool;
-    var rightMargin = (markdown.parent().outerWidth() - markdown.outerWidth()) / 2;
+    let newbool;
+    const rightMargin = (markdown.parent().outerWidth() - markdown.outerWidth()) / 2;
     //for ipad or wider device
     if (rightMargin >= 133) {
         newbool = true;
-        var affixLeftMargin = (tocAffix.outerWidth() - tocAffix.width()) / 2;
-        var left = markdown.offset().left + markdown.outerWidth() - affixLeftMargin;
-        tocAffix.css('left', left + 'px');
+        const affixLeftMargin = (tocAffix.outerWidth() - tocAffix.width()) / 2;
+        const left = markdown.offset().left + markdown.outerWidth() - affixLeftMargin;
+        tocAffix.css('left', `${left}px`);
     } else {
         newbool = false;
     }
@@ -109,10 +113,10 @@ function windowResize() {
         generateScrollspy();
     }
 }
-$(window).resize(function () {
+$(window).resize(() => {
     windowResize();
 });
-$(document).ready(function () {
+$(document).ready(() => {
     windowResize();
     generateScrollspy();
     setTimeout(scrollToHash, 0);
@@ -120,13 +124,13 @@ $(document).ready(function () {
     $('[data-toggle="tooltip"]').tooltip();
 });
 
-function scrollToTop() {
+export function scrollToTop() {
     $('body, html').stop(true, true).animate({
         scrollTop: 0
     }, 100, "linear");
 }
 
-function scrollToBottom() {
+export function scrollToBottom() {
     $('body, html').stop(true, true).animate({
         scrollTop: $(document.body)[0].scrollHeight
     }, 100, "linear");
@@ -134,8 +138,3 @@ function scrollToBottom() {
 
 window.scrollToTop = scrollToTop;
 window.scrollToBottom = scrollToBottom;
-
-module.exports = {
-  scrollToBottom: scrollToBottom,
-  scrollToTop: scrollToTop
-}
diff --git a/public/js/slide.js b/public/js/slide.js
index 1ff388a..63cf64c 100644
--- a/public/js/slide.js
+++ b/public/js/slide.js
@@ -1,67 +1,65 @@
 require('../css/extra.css');
 require('../css/site.css');
 
-var extraModule = require('./extra');
-var md = extraModule.md;
-var updateLastChange = extraModule.updateLastChange;
-var finishView = extraModule.finishView;
+import { md, updateLastChange, finishView } from './extra';
 
-var preventXSS = require('./render').preventXSS;
+import { preventXSS } from './render';
 
-var body = $(".slides").text();
+const body = $(".slides").text();
 
 createtime = lastchangeui.time.attr('data-createtime');
 lastchangetime = lastchangeui.time.attr('data-updatetime');
 updateLastChange();
-var url = window.location.pathname;
-$('.ui-edit').attr('href', url + '/edit');
+const url = window.location.pathname;
+$('.ui-edit').attr('href', `${url}/edit`);
 
-$(document).ready(function () {
+$(document).ready(() => {
     //tooltip
     $('[data-toggle="tooltip"]').tooltip();
 });
 
 function extend() {
-    var target = {};
-    for (var i = 0; i < arguments.length; i++) {
-        var source = arguments[i];
-        for (var key in source) {
+    const target = {};
+
+    for (const source of arguments) {
+        for (const key in source) {
             if (source.hasOwnProperty(key)) {
                 target[key] = source[key];
             }
         }
     }
+
     return target;
 }
 
 // Optional libraries used to extend on reveal.js
-var deps = [{
-    src: serverurl + '/build/reveal.js/lib/js/classList.js',
-    condition: function() {
+const deps = [{
+    src: `${serverurl}/build/reveal.js/lib/js/classList.js`,
+    condition() {
         return !document.body.classList;
     }
 }, {
-    src: serverurl + '/js/reveal-markdown.js',
-    callback: function () {
-        var slideOptions = {
+    src: `${serverurl}/js/reveal-markdown.js`,
+    callback() {
+        const slideOptions = {
             separator: '^(\r\n?|\n)---(\r\n?|\n)$',
             verticalSeparator: '^(\r\n?|\n)----(\r\n?|\n)$'
         };
-        var slides = RevealMarkdown.slidify(body, slideOptions);
+        const slides = RevealMarkdown.slidify(body, slideOptions);
         $(".slides").html(slides);
         RevealMarkdown.initialize();
         $(".slides").show();
     }
 }, {
-    src: serverurl + '/build/reveal.js/plugin/notes/notes.js',
+    src: `${serverurl}/build/reveal.js/plugin/notes/notes.js`,
     async: true,
-    condition: function() {
+    condition() {
         return !!document.body.classList;
     }
 }];
 
 // default options to init reveal.js
-var defaultOptions = {
+const defaultOptions = {
     controls: true,
     progress: true,
     slideNumber: true,
@@ -72,10 +70,10 @@ var defaultOptions = {
 };
 
 // options from yaml meta
-var meta = JSON.parse($("#meta").text());
+const meta = JSON.parse($("#meta").text());
 var options = meta.slideOptions || {};
 
-var view = $('.reveal');
+const view = $('.reveal');
 
 //text language
 if (meta.lang && typeof meta.lang == "string") {
@@ -97,24 +95,24 @@ if (typeof meta.breaks === 'boolean' && !meta.breaks) {
 }
 
 // options from URL query string
-var queryOptions = Reveal.getQueryHash() || {};
+const queryOptions = Reveal.getQueryHash() || {};
 
 var options = extend(defaultOptions, options, queryOptions);
 Reveal.initialize(options);
 
-window.viewAjaxCallback = function () {
+window.viewAjaxCallback = () => {
     Reveal.layout();
 };
 
 function renderSlide(event) {
     if (window.location.search.match( /print-pdf/gi )) {
-        var slides = $('.slides');
+        const slides = $('.slides');
         var title = document.title;
         finishView(slides);
         document.title = title;
         Reveal.layout();
     } else {
-        var markdown = $(event.currentSlide);
+        const markdown = $(event.currentSlide);
         if (!markdown.attr('data-rendered')) {
             var title = document.title;
             finishView(markdown);
@@ -125,16 +123,16 @@ function renderSlide(event) {
     }
 }
 
-Reveal.addEventListener('ready', function (event) {
+Reveal.addEventListener('ready', event => {
     renderSlide(event);
-    var markdown = $(event.currentSlide);
+    const markdown = $(event.currentSlide);
     // force browser redraw
-    setTimeout(function () {
+    setTimeout(() => {
         markdown.hide().show(0);
     }, 0);
 });
 Reveal.addEventListener('slidechanged', renderSlide);
 
-var isMacLike = navigator.platform.match(/(Mac|iPhone|iPod|iPad)/i) ? true : false;
+const isMacLike = navigator.platform.match(/(Mac|iPhone|iPod|iPad)/i) ? true : false;
 
 if (!isMacLike) $('.container').addClass('hidescrollbar');
diff --git a/public/js/syncscroll.js b/public/js/syncscroll.js
index 47d0e1c..c969317 100644
--- a/public/js/syncscroll.js
+++ b/public/js/syncscroll.js
@@ -1,12 +1,13 @@
 // Inject line numbers for sync scroll.
 
-var extra = require('./extra');
-var md = extra.md;
+import markdownitContainer from 'markdown-it-container';
+
+import { md } from './extra';
 
 function addPart(tokens, idx) {
     if (tokens[idx].map && tokens[idx].level === 0) {
-        var startline = tokens[idx].map[0] + 1;
-        var endline = tokens[idx].map[1];
+        const startline = tokens[idx].map[0] + 1;
+        const endline = tokens[idx].map[1];
         tokens[idx].attrJoin('class', 'part');
         tokens[idx].attrJoin('data-startline', startline);
         tokens[idx].attrJoin('data-endline', endline);
@@ -16,48 +17,48 @@ function addPart(tokens, idx) {
 md.renderer.rules.blockquote_open = function (tokens, idx, options, env, self) {
     tokens[idx].attrJoin('class', 'raw');
     addPart(tokens, idx);
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.table_open = function (tokens, idx, options, env, self) {
     addPart(tokens, idx);
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.bullet_list_open = function (tokens, idx, options, env, self) {
     addPart(tokens, idx);
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.list_item_open = function (tokens, idx, options, env, self) {
     tokens[idx].attrJoin('class', 'raw');
     if (tokens[idx].map) {
-        var startline = tokens[idx].map[0] + 1;
-        var endline = tokens[idx].map[1];
+        const startline = tokens[idx].map[0] + 1;
+        const endline = tokens[idx].map[1];
         tokens[idx].attrJoin('data-startline', startline);
         tokens[idx].attrJoin('data-endline', endline);
     }
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.ordered_list_open = function (tokens, idx, options, env, self) {
     addPart(tokens, idx);
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.link_open = function (tokens, idx, options, env, self) {
     addPart(tokens, idx);
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.paragraph_open = function (tokens, idx, options, env, self) {
     addPart(tokens, idx);
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
 md.renderer.rules.heading_open = function (tokens, idx, options, env, self) {
     tokens[idx].attrJoin('class', 'raw');
     addPart(tokens, idx);
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 };
-md.renderer.rules.fence = function (tokens, idx, options, env, self) {
-    var token = tokens[idx],
-      info = token.info ? md.utils.unescapeAll(token.info).trim() : '',
-      langName = '',
-      highlighted;
+md.renderer.rules.fence = (tokens, idx, options, env, self) => {
+    const token = tokens[idx];
+    const info = token.info ? md.utils.unescapeAll(token.info).trim() : '';
+    let langName = '';
+    let highlighted;
 
     if (info) {
         langName = info.split(/\s+/g)[0];
@@ -74,38 +75,33 @@ md.renderer.rules.fence = function (tokens, idx, options, env, self) {
     }
 
     if (highlighted.indexOf('<pre') === 0) {
-        return highlighted + '\n';
+        return `${highlighted}\n`;
     }
 
     if (tokens[idx].map && tokens[idx].level === 0) {
-        var startline = tokens[idx].map[0] + 1;
-        var endline = tokens[idx].map[1];
-        return '<pre class="part" data-startline="' + startline + '" data-endline="' + endline + '"><code' + self.renderAttrs(token) + '>'
-        + highlighted
-        + '</code></pre>\n';
+        const startline = tokens[idx].map[0] + 1;
+        const endline = tokens[idx].map[1];
+        return `<pre class="part" data-startline="${startline}" data-endline="${endline}"><code${self.renderAttrs(token)}>${highlighted}</code></pre>\n`;
     }
 
-    return '<pre><code' + self.renderAttrs(token) + '>'
-        + highlighted
-        + '</code></pre>\n';
+    return `<pre><code${self.renderAttrs(token)}>${highlighted}</code></pre>\n`;
 };
-md.renderer.rules.code_block = function (tokens, idx, options, env, self) {
+md.renderer.rules.code_block = (tokens, idx, options, env, self) => {
     if (tokens[idx].map && tokens[idx].level === 0) {
-        var startline = tokens[idx].map[0] + 1;
-        var endline = tokens[idx].map[1];
-        return '<pre class="part" data-startline="' + startline + '" data-endline="' + endline + '"><code>' + md.utils.escapeHtml(tokens[idx].content) + '</code></pre>\n';
+        const startline = tokens[idx].map[0] + 1;
+        const endline = tokens[idx].map[1];
+        return `<pre class="part" data-startline="${startline}" data-endline="${endline}"><code>${md.utils.escapeHtml(tokens[idx].content)}</code></pre>\n`;
     }
-    return '<pre><code>' + md.utils.escapeHtml(tokens[idx].content) + '</code></pre>\n';
+    return `<pre><code>${md.utils.escapeHtml(tokens[idx].content)}</code></pre>\n`;
 };
 function renderContainer(tokens, idx, options, env, self) {
     tokens[idx].attrJoin('role', 'alert');
     tokens[idx].attrJoin('class', 'alert');
-    tokens[idx].attrJoin('class', 'alert-' + tokens[idx].info.trim());
+    tokens[idx].attrJoin('class', `alert-${tokens[idx].info.trim()}`);
     addPart(tokens, idx);
-    return self.renderToken.apply(self, arguments);
+    return self.renderToken(...arguments);
 }
 
-var markdownitContainer = require('markdown-it-container');
 md.use(markdownitContainer, 'success', { render: renderContainer });
 md.use(markdownitContainer, 'info', { render: renderContainer });
 md.use(markdownitContainer, 'warning', { render: renderContainer });
@@ -117,18 +113,18 @@ window.syncscroll = true;
 window.preventSyncScrollToEdit = false;
 window.preventSyncScrollToView = false;
 
-var editScrollThrottle = 5;
-var viewScrollThrottle = 5;
-var buildMapThrottle = 100;
+const editScrollThrottle = 5;
+const viewScrollThrottle = 5;
+const buildMapThrottle = 100;
 
-var viewScrolling = false;
-var editScrolling = false;
+let viewScrolling = false;
+let editScrolling = false;
 
-var editArea = null;
-var viewArea = null;
-var markdownArea = null;
+let editArea = null;
+let viewArea = null;
+let markdownArea = null;
 
-function setupSyncAreas(edit, view, markdown) {
+export function setupSyncAreas(edit, view, markdown) {
     editArea = edit;
     viewArea = view;
     markdownArea = markdown;
@@ -136,26 +132,24 @@ function setupSyncAreas(edit, view, markdown) {
     viewArea.on('scroll', _.throttle(syncScrollToEdit, viewScrollThrottle));
 }
 
-var scrollMap, lineHeightMap, viewTop, viewBottom;
+let scrollMap, lineHeightMap, viewTop, viewBottom;
 
-window.viewAjaxCallback = clearMap;
-
-function clearMap() {
+export function clearMap() {
     scrollMap = null;
     lineHeightMap = null;
     viewTop = null;
     viewBottom = null;
 }
+window.viewAjaxCallback = clearMap;
 
-var buildMap = _.throttle(buildMapInner, buildMapThrottle);
+const buildMap = _.throttle(buildMapInner, buildMapThrottle);
 
 // Build offsets for each line (lines can be wrapped)
 // That's a bit dirty to process each line everytime, but ok for demo.
 // Optimizations are required only for big texts.
 function buildMapInner(callback) {
     if (!viewArea || !markdownArea) return;
-    var i, offset, nonEmptyList, pos, a, b, _lineHeightMap, linesCount,
-        acc, _scrollMap;
+    let i, offset, nonEmptyList, pos, a, b, _lineHeightMap, linesCount, acc, _scrollMap;
 
     offset = viewArea.scrollTop() - viewArea.offset().top;
     _scrollMap = [];
@@ -165,10 +159,10 @@ function buildMapInner(callback) {
     viewBottom = viewArea[0].scrollHeight - viewArea.height();
 
     acc = 0;
-    var lines = editor.getValue().split('\n');
-    var lineHeight = editor.defaultTextHeight();
+    const lines = editor.getValue().split('\n');
+    const lineHeight = editor.defaultTextHeight();
     for (i = 0; i < lines.length; i++) {
-        var str = lines[i];
+        const str = lines[i];
 
         _lineHeightMap.push(acc);
 
@@ -177,7 +171,7 @@ function buildMapInner(callback) {
             continue;
         }
 
-        var h = editor.heightAtLine(i + 1) - editor.heightAtLine(i);
+        const h = editor.heightAtLine(i + 1) - editor.heightAtLine(i);
         acc += Math.round(h / lineHeight);
     }
     _lineHeightMap.push(acc);
@@ -191,10 +185,10 @@ function buildMapInner(callback) {
     // make the first line go top
     _scrollMap[0] = viewTop;
 
-    var parts = markdownArea.find('.part').toArray();
+    const parts = markdownArea.find('.part').toArray();
     for (i = 0; i < parts.length; i++) {
-        var $el = $(parts[i]),
-            t = $el.attr('data-startline') - 1;
+        const $el = $(parts[i]);
+        let t = $el.attr('data-startline') - 1;
         if (t === '') {
             return;
         }
@@ -229,9 +223,9 @@ function buildMapInner(callback) {
 }
 
 // sync view scroll progress to edit
-var viewScrollingTimer = null;
+let viewScrollingTimer = null;
 
-function syncScrollToEdit(event, preventAnimate) {
+export function syncScrollToEdit(event, preventAnimate) {
     if (currentMode != modeType.both || !syncscroll || !editArea) return;
     if (preventSyncScrollToEdit) {
         if (typeof preventSyncScrollToEdit === 'number') {
@@ -242,15 +236,15 @@ function syncScrollToEdit(event, preventAnimate) {
         return;
     }
     if (!scrollMap || !lineHeightMap) {
-        buildMap(function () {
+        buildMap(() => {
             syncScrollToEdit(event, preventAnimate);
         });
         return;
     }
     if (editScrolling) return;
 
-    var scrollTop = viewArea[0].scrollTop;
-    var lineIndex = 0;
+    const scrollTop = viewArea[0].scrollTop;
+    let lineIndex = 0;
     for (var i = 0, l = scrollMap.length; i < l; i++) {
         if (scrollMap[i] > scrollTop) {
             break;
@@ -258,8 +252,8 @@ function syncScrollToEdit(event, preventAnimate) {
             lineIndex = i;
         }
     }
-    var lineNo = 0;
-    var lineDiff = 0;
+    let lineNo = 0;
+    let lineDiff = 0;
     for (var i = 0, l = lineHeightMap.length; i < l; i++) {
         if (lineHeightMap[i] > lineIndex) {
             break;
@@ -269,14 +263,14 @@ function syncScrollToEdit(event, preventAnimate) {
         }
     }
 
-    var posTo = 0;
-    var topDiffPercent = 0;
-    var posToNextDiff = 0;
-    var scrollInfo = editor.getScrollInfo();
-    var textHeight = editor.defaultTextHeight();
-    var preLastLineHeight = scrollInfo.height - scrollInfo.clientHeight - textHeight;
-    var preLastLineNo = Math.round(preLastLineHeight / textHeight);
-    var preLastLinePos = scrollMap[preLastLineNo];
+    let posTo = 0;
+    let topDiffPercent = 0;
+    let posToNextDiff = 0;
+    const scrollInfo = editor.getScrollInfo();
+    const textHeight = editor.defaultTextHeight();
+    const preLastLineHeight = scrollInfo.height - scrollInfo.clientHeight - textHeight;
+    const preLastLineNo = Math.round(preLastLineHeight / textHeight);
+    const preLastLinePos = scrollMap[preLastLineNo];
 
     if (scrollInfo.height > scrollInfo.clientHeight && scrollTop >= preLastLinePos) {
         posTo = preLastLineHeight;
@@ -293,7 +287,7 @@ function syncScrollToEdit(event, preventAnimate) {
     if (preventAnimate) {
         editArea.scrollTop(posTo);
     } else {
-        var posDiff = Math.abs(scrollInfo.top - posTo);
+        const posDiff = Math.abs(scrollInfo.top - posTo);
         var duration = posDiff / 50;
         duration = duration >= 100 ? duration : 100;
         editArea.stop(true, true).animate({
@@ -311,9 +305,9 @@ function viewScrollingTimeoutInner() {
 }
 
 // sync edit scroll progress to view
-var editScrollingTimer = null;
+let editScrollingTimer = null;
 
-function syncScrollToView(event, preventAnimate) {
+export function syncScrollToView(event, preventAnimate) {
     if (currentMode != modeType.both || !syncscroll || !viewArea) return;
     if (preventSyncScrollToView) {
         if (typeof preventSyncScrollToView === 'number') {
@@ -324,20 +318,20 @@ function syncScrollToView(event, preventAnimate) {
         return;
     }
     if (!scrollMap || !lineHeightMap) {
-        buildMap(function () {
+        buildMap(() => {
             syncScrollToView(event, preventAnimate);
         });
         return;
     }
     if (viewScrolling) return;
 
-    var lineNo, posTo;
-    var topDiffPercent, posToNextDiff;
-    var scrollInfo = editor.getScrollInfo();
-    var textHeight = editor.defaultTextHeight();
+    let lineNo, posTo;
+    let topDiffPercent, posToNextDiff;
+    const scrollInfo = editor.getScrollInfo();
+    const textHeight = editor.defaultTextHeight();
     lineNo = Math.floor(scrollInfo.top / textHeight);
     // if reach the last line, will start lerp to the bottom
-    var diffToBottom = (scrollInfo.top + scrollInfo.clientHeight) - (scrollInfo.height - textHeight);
+    const diffToBottom = (scrollInfo.top + scrollInfo.clientHeight) - (scrollInfo.height - textHeight);
     if (scrollInfo.height > scrollInfo.clientHeight && diffToBottom > 0) {
         topDiffPercent = diffToBottom / textHeight;
         posTo = scrollMap[lineNo + 1];
@@ -353,7 +347,7 @@ function syncScrollToView(event, preventAnimate) {
     if (preventAnimate) {
         viewArea.scrollTop(posTo);
     } else {
-        var posDiff = Math.abs(viewArea.scrollTop() - posTo);
+        const posDiff = Math.abs(viewArea.scrollTop() - posTo);
         var duration = posDiff / 50;
         duration = duration >= 100 ? duration : 100;
         viewArea.stop(true, true).animate({
@@ -369,10 +363,3 @@ function syncScrollToView(event, preventAnimate) {
 function editScrollingTimeoutInner() {
     editScrolling = false;
 }
-
-module.exports = {
-  setupSyncAreas: setupSyncAreas,
-  clearMap: clearMap,
-  syncScrollToEdit: syncScrollToEdit,
-  syncScrollToView: syncScrollToView
-};