function doSave() {
localStorage.qrcode = inp.value
save.disabled = true
}
function generateQRCode() {
let txt = inp.value
while (!txt) {
txt = prompt("Enter some text", location.href)
inp.value = txt
}
QR.innerHTML = ""; new QRCode(QR, txt)
save.disabled = localStorage.qrcode == inp.value
inp.selectionEnd = txt.length
inp.selectionStart = 0; inp.focus()
}