Cannot change code

Hello

The code (editorCode) is initially correct, but cannot change it afterwards (show correct in alert):

{{> CodeMirror id="edJs" name="someName" options=editorOptions code=editorCode }}

editorOptions: function() {
    return {
      lineNumbers: true,
      mode: "javascript"
    }
  },
  editorCode: function() {
    alert(this.js);
    return this.js;
  }
