diff --git a/lib/ace/mode/javascript.js b/lib/ace/mode/javascript.js
index 866da638..821cc9b9 100644
--- a/lib/ace/mode/javascript.js
+++ b/lib/ace/mode/javascript.js
@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2010, Ajax.org B.V.
  * All rights reserved.
- * 
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *     * Redistributions of source code must retain the above copyright
@@ -14,7 +14,7 @@
  *     * Neither the name of Ajax.org B.V. nor the
  *       names of its contributors may be used to endorse or promote products
  *       derived from this software without specific prior written permission.
- * 
+ *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
@@ -32,6 +32,7 @@ define(function(require, exports, module) {
 "use strict";
 
 var oop = require("../lib/oop");
+var lang = require("ace/lib/lang");
 var TextMode = require("./text").Mode;
 var Tokenizer = require("../tokenizer").Tokenizer;
 var JavaScriptHighlightRules = require("./javascript_highlight_rules").JavaScriptHighlightRules;
@@ -51,32 +52,41 @@ oop.inherits(Mode, TextMode);
 
 (function() {
 
+    this.lineCommentStart = "//";
+    this.toggleCommentLines = function(state, session, startRow, endRow) {
+        var doc = session.doc;
+        var str = this.lineCommentStart;
+        var regexpStart = new RegExp("^\\s*"+lang.escapeRegExp(str) + " ?");
 
-    this.toggleCommentLines = function(state, doc, startRow, endRow) {
-        var outdent = true;
-        var re = /^(\s*)\/\//;
-
-        for (var i=startRow; i<= endRow; i++) {
-            if (!re.test(doc.getLine(i))) {
-                outdent = false;
-                break;
-            }
+        function isCommented(str) {
+            return regexpStart.test(str);
         }
 
-        if (outdent) {
-            var deleteRange = new Range(0, 0, 0, 0);
-            for (var i=startRow; i<= endRow; i++)
-            {
+        var removeComment = true;
+        var minSpace = Infinity;
+        var indentations = [];
+
+        for (var i = startRow; i <= endRow; i++) {
+            var line = doc.getLine(i);
+            var indent = line.search(/\S|$/);
+            indentations[i] = indent;
+            if (indent < minSpace)
+                minSpace = indent;
+            if (removeComment && !isCommented(line))
+                removeComment = false;
+        }
+
+        if (removeComment) {
+            for (var i = startRow; i <= endRow; i++) {
                 var line = doc.getLine(i);
-                var m = line.match(re);
-                deleteRange.start.row = i;
-                deleteRange.end.row = i;
-                deleteRange.end.column = m[0].length;
-                doc.replace(deleteRange, m[1]);
+                var m = line.match(regexpStart);
+                doc.removeInLine(i, indentations[i], m[0].length);
+            }
+        } else {
+            str += " ";
+            for (var i = startRow; i <= endRow; i++) {
+                doc.insertInLine({row: i, column: minSpace}, str);
             }
-        }
-        else {
-            doc.indentRows(startRow, endRow, "//");
         }
     };
 
@@ -90,7 +100,7 @@ oop.inherits(Mode, TextMode);
         if (tokens.length && tokens[tokens.length-1].type == "comment") {
             return indent;
         }
-        
+
         if (state == "start" || state == "no_regex") {
             var match = line.match(/^.*(?:\bcase\b.*\:|[\{\(\[])\s*$/);
             if (match) {
@@ -119,7 +129,7 @@ oop.inherits(Mode, TextMode);
     this.autoOutdent = function(state, doc, row) {
         this.$outdent.autoOutdent(doc, row);
     };
-    
+
     this.createWorker = function(session) {
         var worker = new WorkerClient(["ace"], "ace/mode/javascript_worker", "JavaScriptWorker");
         worker.attachToDocument(session.getDocument());
@@ -127,11 +137,11 @@ oop.inherits(Mode, TextMode);
         worker.on("jslint", function(results) {
             session.setAnnotations(results.data);
         });
-        
+
         worker.on("terminate", function() {
             session.clearAnnotations();
         });
-        
+
         return worker;
     };