input mac address

<input id="macAddress" type="text" maxlength="17"></input>  var macAddress = document.getElementById("macAddress");  function formatMAC(e) {     var r = /([a-f0-9]{2})([a-f0-9]{2})/i,         str = e.target.value.replace(/[^a-f0-9]/ig, "");      while (r.test(str)) {         str = str.replace(r, '$1' + ':' + '$2');     }      e.target.value = str.slice(0, 17); };  macAddress.addEventListener("keyup", formatMAC, false);