improve btcpayserver lnurlwnfc.js

lnurlwnfc.js

Vue.component("LNURLWithdrawContactless", {
    data: function () {
        return {
            supported: 'NDEFReader' in window,
            scanning: false,
            submitting: false,
            readerAbortController: null,
        }
    },
    methods: {
        startScan: async function () {
            try {
                if (this.scanning || this.submitting) {
                    return;
                }
                const self = this;
                self.submitting = false;
                self.scanning = true;
                if (!this.supported) {
                    const result = prompt("enter lnurl withdraw");
                    if (result) {
                        self.sendData.bind(self)(result);
                        return;
                    }
                    self.scanning = false;
                }
                ndef = new NDEFReader()
                self.readerAbortController = new AbortController()
                await ndef.scan({signal: self.readerAbortController.signal})

                ndef.addEventListener('readingerror', () => {
                    self.scanning = false;
                    self.readerAbortController.abort()
                })

                ndef.addEventListener('reading', ({message, serialNumber}) => {
                    //Decode NDEF data from tag
                    const record = message.records[0]
                    const textDecoder = new TextDecoder('utf-8')
                    const lnurl = textDecoder.decode(record.data)

                    //User feedback, show loader icon
                    self.scanning = false;
                    self.sendData.bind(self)(lnurl);

                })
            } catch(e) {
                self.scanning = false;
                self.submitting = false;
            }
        },
        sendData: function (lnurl) {

            this.submitting = true;
            //Post LNURLW data to server
            var xhr = new XMLHttpRequest()
            xhr.open('POST', window.lnurlWithdrawSubmitUrl, true)
            xhr.setRequestHeader('Content-Type', 'application/json')
            xhr.send(JSON.stringify({lnurl, destination: this.$parent.srvModel.btcAddress}))
            const self = this;
            //User feedback, reset on failure
            xhr.onload = function () {
                if (xhr.readyState === xhr.DONE) {
                    console.log(xhr.response);
                    console.log(xhr.responseText);
                    self.scanning = false;
                    self.submitting = false;
                    
                    if(self.readerAbortController) {
                        self.readerAbortController.abort()
                    }

                    try {
                        var data = JSON.parse(xhr.response)

                        if(data && data.status == "ERROR") {
                            alert(data.reason)
                        }
                    } catch (err) {
                        alert("Error parsing response.")
                    }
                }
            }
        }
    }
});