[Solved] Copy values if checkbox is checked

by 


function billingFunction() {
  if (document.getElementById('same').checked) {
    var shipinfo = document.getElementById('shippingName').value;
    var billinfo = document.getElementById('shippingZip').value;

    document.getElementById('billingName').value = shipinfo;
    document.getElementById('billingZip').value = billinfo;
  } else {
    document.getElementById('billingName').value="";
    document.getElementById('billingZip').value="";
  }
}

use this

solved Copy values if checkbox is checked