问如何侦听Ace编辑器更改事件并作出反应

EN

<div class="container">
  <div class="panel panel-default">
    <div class="panel-heading">
      <h3 class="panel-title">Editor</h3>
    </div>
    <div class="panel-body">
      <a href="#" onclick="update()">go</a>
      <div id="editor" onChange="update()">function foo(items) { var x = "All this is syntax highlighted"; return x; }
      </div>
    </div>
  </div>
  <div id="output">Output is here (click 'go' and write HTML and js in the editor) </div>
  <div class="text-center">---End of editor---</div>
</div>

var editor = ace.edit("editor");
editor.setTheme("ace/theme/monokai");
editor.getSession().setMode("ace/mode/javascript");
editor.getSession().on('change', function() {
  update()
});

function update() //writes in <div> with id=output
{
  var val = editor.getSession().getValue();
  var divecho = document.getElementById("output");
  divecho.innerHTML = val;
}

#editor {
  /** Setting height is also important, otherwise the editor won’t show up **/
  height: 300px;
}

#output {
  height: 100px;
}