excel

 previewExcel(url) {
      let previewExcelUrl = 'https://view.officeapps.live.com/op/view.aspx?src='
      if (!url) {
        return this.$message.warn('无文件链接，无法预览')
      }
      window.open(`${previewExcelUrl}${url || ''}`, '_blank')
    },