Alternative to toLocaleString() in ExtendScript?

[tardigrade01]

As far as I can tell and after many attempts, this method doesn't work in ES. Does anyone know of an alternative for automatically adding commas to large numbers?

[tardigrade01]

for what it's worth, this is my current, hacky workaround:

var data = {
  number: 12345
}
num = data.number.toString();
if (num.length > 3){
  data.number = num.substring(0, num.length-3) + "," + num.substring(num.length-3);
}