element ui图片上传方法

          <!--商品图片-->
          <template v-slot:product_cover>
            <el-upload
              list-type="picture-card"
              name="cover"
              accept="image/png, image/jpeg,image/jpg"
              :multiple="multiple"
              :action="cover_upload_action"
              :headers="upload_header"
              :on-success="cover_upload_success"
              :on-progress="cover_on_process"
              :file-list="cover"
              :on-preview="handlePictureCardPreview"
              :on-remove="handleRemove"
              :limit="6"
              :on-exceed='on_exceed'>
              <i class="el-icon-plus">添加主图</i>
            </el-upload>
            <el-dialog :visible.sync="dialogVisible">
              <img width="100%" :src="dialogImageUrl" alt="">
            </el-dialog>          </template>

 cover_upload_success(resp, file, fileList){
      console.log(fileList)
      let is_last = true;
      fileList.forEach(function(val, index){
       if(typeof val.response == "undefined" && !val.hasOwnProperty('img_id')){
         is_last = false;
       }
      })
      if(is_last){
        fileList.forEach(function(val){
          if(typeof val.response != "undefined")
          {
            store.commit('product/PUSH_COVER',val.response.data);
          }
        })
      }
    },