Adding fadeout to preload screen

[alqur]

Hi, Im trying to add a fadeout as opposed to an abrupt ending to my preload screen. Can't get anything to work. Can anyone help?

<div id="preloader">

</div>

<script type="text/javascript">

(

function()

{

var preload = document.getElementById("preloader");

var isMobile = /iPhone|iPad|iPod|Android/i.test(navigator.userAgent);

var loading = 0;

var id = setInterval(frame, 30);

function frame()

{

if(loading == 70)

{

clearInterval(id);

}

else

{

loading = loading + 1;

if(! isMobile)

{

if(loading == 60)

{

preload.style.opacity = "0";

preload.style.display = "none";

}