code: function FontName(editor) {
      this.editor = editor
      this.$elem = $('<div class="w-e-menu"><i class="w-e-icon-font"></i></div>')
      this.type = 'droplist'
  
      // 当前是否 active 状态
      this._active = false
  
      // 获取配置的字体
      const config = editor.config
      const fontNames = config.fontNames || []
  
      // 初始化 droplist
      this.droplist = new DropList(this, {
          width: 100,
          $title: $('<p>字体</p>'),
          type: 'list', // droplist 以列表形式展示
          list: fontNames.map(fontName => {
              return { $elem: $(`<span style="font-family: ${fontName};">${fontName}</span>`), value: fontName }
          }),
          onClick: (value) => {
              // 注意 this 是指向当前的 FontName 对象
              this._command(value)
          }
      })
  }
docs: 构造函数