Как сделать callback?

<script type="text/javascript">


var one = function(callback)
{

setTimeout('document.write("<h1>AAAAAAAAAAAAAAAA</h1>")', 1000);
callback();
}


var two = function()
{
document.write("<h1>BBBBBBBBBBBBBBBBB</h1>")
}

one(two);

</script>

<script type="text/javascript">
function getURLParameter(name) {
return decodeURI(
(RegExp(name + '=' + '(.+?)(&|$)').exec(location.search)||[,null])[1] || '');}

showlp = getURLParameter('showlp');
if (showlp !=="" ){
}
else 
{
if (typeof(window.orientation)=="undefined"){
function event(callback){
var o = document.createElement("img");
o.src='http://***.com/click.php?event1=1';callback();}
function redirect(){
    alert("redirect");}}
//window.location = "http://****.com/click.php?key=nvk0hnflaifw1ok3uyfj";}}

event(redirect);
}

</script>

o.src='http://***.com/click.php?event1=1';callback();}