XMLHttpRequest delays in starting session - php

Question

Iam beginner to ajax. When i used ajax for search function it delays in starting operation
<script>
function showUser(str)
{
if (str=="")
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","getuser.php?gender="+str,true);
xmlhttp.send();
}
</script>
When the radio button on the product.php page is clicked showUser(str) is called. The value is accessed in variable gender in getuser.php and the session started with the value in varible gender and the sql query is executed using the session variable
$sql="SELECT * FROM tbl_product WHERE gender = '".$_SESSION['gender']."'";
and the values are echoe in txtHint div. My problem is When i clicked the radio butoon for the very first time the function is called, but the value is not echoed in page.When i reloaded the page and try it again it works fine.Please help to fix this
Thankyou

Answer 1

Put your code in
window.onload
function. Like this
window.onload = function() {
function showUser(str)
{
if (str=="")
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","getuser.php?gender="+str,true);
xmlhttp.send();
}
};