getEwm(url){
document.getElementById("qrcode").innerHTML = "";
var qrcode = new QRCode(this.$refs.qrCodeUrl, {
text: url,
width: 200,
height: 200,
colorDark: '#000000',
colorLight: '#ffffff',
correctLevel: QRCode.CorrectLevel.H
})
},
即生成二维码之前先将存放二维码的标签清空
document.getElementById("qrcode").innerHTML = "";