This one may be simple. Javascript alerts are not working on MSIE for Xbox One. I've tested them on a PC, OSX, Nokia phone, iPhone.
Javascript obviously works as I'm using socket.io.
Here is the code:
function changeGamerTag() {
if (socket.socket.connected) {
socket.emit('partyup add user', prompt("Enter GAMERTAG: ") + '['+ masterrace + ']');
} else {
alert('Party server offline.');
}
}