firewalletbrowser/templates/assets/js/receive.min.js

function copyAddress(){var e=document.getElementById("copyLink").getAttribute("address"),t=document.createElement("input");t.value=e,document.body.appendChild(t),t.select(),t.setSelectionRange(0,99999),navigator.clipboard.writeText(t.value),document.body.removeChild(t),document.getElementById("copyLink").innerHTML="Copied!"}