qrcode使用

1
<canvas id="qrcodeImage">
</canvas>
2
import QRCode from 'qrcode';
3
  qrcode(res){
            let toUtf8 = function (str) {
                let out, i, len, c;
                out = "";
                len = str.length;
                for (i = 0; i < len; i++) {
                    c = str.charCodeAt(i);
                    if ((c >= 0x0001) && (c <= 0x007F)) {
                        out += str.charAt(i);
                    } else if (c > 0x07FF) {
                        out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
                        out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
                        out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
                    } else {
                        out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
                        out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
                    }
                }
                return out;
            };
            QRCode.toCanvas(document.getElementById('qrcodeImage'),toUtf8(res),{
                width: 200,
                height:200,
            }, function (error) {
              if (error) console.error(error)
              console.log('success!');
            })
        },
        "qrcode": "^1.5.3",