element 上传图片限制

 :before-upload = "handleUpload"

 // 上传限制格式
      handleUpload(file) {
        console.log(file);
        const isIMG =
          file.name.split('.')[file.name.split('.').length - 1] === 'jpg' ||
          file.name.split('.')[file.name.split('.').length - 1] === 'jpeg' ||
          file.name.split('.')[file.name.split('.').length - 1] === 'png' ||
          file.name.split('.')[file.name.split('.').length - 1] === 'rar' ||
          file.name.split('.')[file.name.split('.').length - 1] === 'zip' ||
          file.name.split('.')[file.name.split('.').length - 1] === 'pdf' ||
          file.name.split('.')[file.name.split('.').length - 1] === 'doc' ||
          file.name.split('.')[file.name.split('.').length - 1] === 'docx'

        console.log(isIMG);
        //20M
        const isLt = file.size / 20480000 <= 1
        if (!isIMG) {
          this.$message.error('上传文件只支持pdf,docx,doc,jpg,png,rar,zip格式!')
          return false
        }
        if (!isLt) {
          this.$message.error('上传文件大小不能超过20M!')
          return false
        }
        return true
      },