在外部例如uni-fab的点击事件中调用onClick，或者show，都不会弹出文件选择器无效，怎么解决呢

<lsj-upload  
    ref="upload"  
      height="80rpx"  
        :instantly="true"  
      :option="option"  
      :formats="formats"  
        @uploadEnd="uploadEnd"  
    >  

    <button style="float: right;" size="mini" class="bg-primary">上传文件</button>  
    </lsj-upload>  
    <uni-fab horizontal="right" @fabClick="fabClick"></uni-fab>  

    function fabClick() {  
        upload.value.onClick();  

    }