上传图片后依旧无法删除

```javascript
imgDel(pos){
      let filename = this.img_file[pos]['name'];
      let res = this.$refs.md.$refs.toolbar_left.$imgDelByFilename(filename);
      console.log(res);
      if(res){
        alert("删除成功!")
        // delete this.img_file[pos];
      }else {
        alert("删除失败!")
      }
},
```