text: /*
      undo-menu
  */
  import $ from '../../util/dom-core.js'
  
  // 构造函数
  function Undo(editor) {
      this.editor = editor
      this.$elem = $(
          `<div class="w-e-menu">
              <i class="icon w-e-icon w-e-icon-undo"></i>
          </div>`
      )
      this.type = 'click'
  
      // 当前是否 active 状态
      this._active = false
  }
  
  // 原型
  Undo.prototype = {
      constructor: Undo,
  
      // 点击事件
      onClick: function (e) {
          // 点击菜单将触发这里
  
          const editor = this.editor
  
          // 执行 undo 命令
          editor.cmd.do('undo')
      }
  }
  
  export default Undo