Edit in JSFiddle

   var textarea = $('#content');

   var editor = ace.edit("editor");
   editor.setTheme("ace/theme/twilight");
   editor.getSession().setMode("ace/mode/javascript");

   editor.getSession().on('change', function () {
       textarea.val(editor.getSession().getValue());
   });

   textarea.val(editor.getSession().getValue());

   $("#toggletextarea-btn").on('click', function () {
       textarea.toggle();
       $(this).text(function (i, text) {
           return text === "Show Content" ? "Hide Content" : "Show Content";
       });
   });

   $("#alertcontent-btn").on('click', function () {
       alert(textarea.val());
   });

<div class="container">
    <div class="panel panel-default">
        <div class="panel-heading">
             <span class="panel-title">Editor</span>
        </div>
        <div class="panel-body">
            <div class="row">
                <h4>Ace Editor</h4>
                <div class="col-md-6">
                    <div id="editor">function foo(items) {
    var x = "All this is syntax highlighted";
    return x;
}</div>
                </div>
                <div class="col-md-6">
                    <h4>Textarea</h4>
                    <textarea class="col-md-6" name="content" id="content" rows="5" cols="70" disabled="disabled"></textarea>
                </div>
            </div>
        </div>
    </div>
    <div class="text-center">---End of editor---</div>
    <button class="btn btn-primary" id="toggletextarea-btn">Hide TextArea</button>
    <button class="btn btn-default" id="alertcontent-btn">Alert Content</button>
    <br/>
    <br/>
</div>

#editor {
    /** Setting height is also important, otherwise editor wont showup**/
    height: 175px;
}