下载qrcode生成的二维码

// 生产二维码
async handleVerification($index, row) {
      try {
        this.QRImage = await QRCode.toDataURL(`${qrcodeUrl}#/pages/welfareMall/redeemConfirm?id=${row.id}`)
      } catch (e) {
        this.$message({
          type: "error",
          message: "获取二维码失败，请重试"
        })
        return this.verificationVisible = false
      }
      this.verificationVisible = true
    },
// 下载二维码
downloadBase64AsImage(base64Data, fileName) {
            const link = document.createElement('a');
            link.href = base64Data;
            link.download = fileName; // 文件名
            const clickEvent = new MouseEvent('click', { bubbles: true });
            link.dispatchEvent(clickEvent);
        },

// 调用
this.downloadBase64AsImage(this.QRImage, '兑换凭证二维码');