vue custom instruction, the method is called automatically download

  directives: {
    clickDown: {
      inserted (el, binding, item) {
        if (+binding.value.item.fromId === +item.context.userId) {
          // console.log(item.context) item.contex为vue的实例,也就是页面中的this
          // downloadFile() 下载文件的方法
          item.context.downloadFile(binding.value.item)
        }
      }
    }
  },

                      <div class="chat-item-msg-file"
                           v-clickDown="{ item: item }"
                        <span class="icon-box">