working clicking on side div line number to set line number hash and then on visiting scrolling back into view

src/static/css/iframe_editor.css

@@ -101,6 +101,7 @@ body.mozilla, body.safari {
   font-size: 9px;
   padding: 0 14px 0 10px;
   font-family: monospace;
+  cursor: pointer;
 }
 .plugin-ep_author_neat #sidedivinner.authorColors .line-number {
   padding-right: 10px;

src/static/js/pad_editor.js

@@ -1,3 +1,4 @@
+'use strict';
 /**
  * This code is mostly from the old Etherpad. Please help us to comment this code.
  * This helps other people to understand this code better and helps them to improve it.
@@ -29,7 +30,7 @@ const padeditor = (function () {
   let pad = undefined;
   let settings = undefined;
 
-  var self = {
+  const self = {
     ace: null,
     // this is accessed directly from other files
     viewZoom: 100,
@@ -41,6 +42,33 @@ const padeditor = (function () {
       function aceReady() {
         $('#editorloadingbox').hide();
         if (readyFunc) {
+          // If a number is in the URI IE #L124 go to that line number
+          const lineNumber = window.location.hash.substr(1);
+          if (lineNumber) {
+            if (lineNumber[0] === 'L') {
+              const lineNumberInt = parseInt(lineNumber.replace('L', ''));
+              const $inner = $('iframe[name="ace_outer"]').contents().find('iframe')
+                  .contents().find('#innerdocbody');
+              const line = $inner.find(`div:nth-child(${lineNumberInt})`);
+              if (line.length !== 0) {
+                let offsetTop = line.offset().top;
+                const $outerdoc = $('iframe[name="ace_outer"]').contents().find('#outerdocbody');
+                offsetTop += parseInt($outerdoc.css('padding-top').replace('px', ''));
+                offsetTop += parseInt($inner.css('padding-top').replace('px', ''));
+                const $outerdocHTML = $('iframe[name="ace_outer"]').contents()
+                    .find('#outerdocbody').parent();
+                $outerdoc.css({top: `${offsetTop}px`}); // Chrome
+                $outerdocHTML.animate({scrollTop: offsetTop}); // needed for FF
+              }
+            }
+          }
+          const $outerdoc = $('iframe[name="ace_outer"]').contents().find('#outerdocbody');
+          // Listen for clicks on sidediv items
+          $outerdoc.find('#sidedivinner').on('click', 'div', function() {
+            const lineNumber = $(this).index() + 1;
+            window.location.hash = 'L' + lineNumber;
+          })
+
           readyFunc();
         }
       }