element el-upload檔案上傳覆蓋第一個檔案的實現

<el-upload
  class="upload-demo"
  action="https://jsonplaceholder.typicode.com/posts/"
  accept=".xls, .xlsx"
  :on-preview="handlePreview"
  :on-remove="handleRemove"
  :before-remove="beforeRemove"
  multiple
  :limit="1"
  :on-exceed="handleExceed"
  :file-list="fileList">
  <el-button size="small" type="primary">點選上傳</el-button>
  <div slot="tip" class="el-upload__tip">只能上傳jpg/png檔案，且不超過500kb</div>
</el-upload>
<script>
  export default {
    data() {
      return {
        fileList: [{name: 'food.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}, {name: 'food2.jpeg', url: 'https://fuss10.elemecdn.com/3/63/4e7f3a15429bfda99bce42a18cdd1jpeg.jpeg?imageMogr2/thumbnail/360x360/format/webp/quality/100'}]
      };
    },
    methods: {
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      handlePreview(file) {
        console.log(file);
      },
      handleExceed(files, fileList) {
        this.$message.warning(`當前限制選擇 3 個檔案，本次選擇了 ${files.length} 個檔案，共選擇了 ${files.length + fileList.length} 個檔案`);
      },
      beforeRemove(file, fileList) {
        return this.$confirm(`確定移除 ${ file.name }？`);
      }
    }
  }
</script>

<el-upload 
    :action="uploadActionUrl"
    accept="image/jpeg,image/gif,image/png"
    multiple
    :limit="1"
    :on-exceed="handleExceed"    
    :on-error="uploadError"
    :on-success="uploadSuccess"
    :on-remove="onRemoveTxt"
    :before-upload="onBeforeUpload"
    :file-list="files">
    <el-button size="small" type="primary">點選上傳</el-button>
    <div slot="tip" class="el-upload__tip">請上傳圖片格式檔案</div>
</el-upload>

      handleChange(file, fileList) {
        this.ebsFileList = fileList;
        this.ebsErrorImport = '';
        if (fileList.length > 1) {
               fileList.splice(0, 1);
               this.$message.error('只能上傳一個檔案');
           }
      }