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 = "";