vue实现修改图片后实时更新

<el-upload
  action="string"
  :http-request="uploadImg"
  :show-file-list="false">
  <el-button v-perm="'b:img:upload'" size="small" type="primary">点击上传</el-button>
</el-upload>
<div class="imgStyle mar_top10">
  <img width="100%" :src="dialogImageUrl" alt="">
</div>

method : {
  uploadImg(item) {
   var isFlag = (item.file.type == 'image/jpeg' || item.file.type == 'image/png')? true : false;
   if(!isFlag){
    this.$message({
     type: 'warning',
     message: '上传图片只能是 JPG、PNG 格式!'
    })
    return false
   }
   let formData = new FormData();
   formData.append('file', item.file);//若查看可使用 formData.get('file')
   api.updateShareBack(formData).then(res => {
    var res = res.data;
    if(res.code == 200){
     this.$message({
      type: 'success',
      message: '上传成功'
     })
     this.dialogImageUrl = res.data + '?' + new Date().getTime();//new Date().getTime()使用时间戳更换每次的修改的图片
    }
   })
  }
}