glitch in Javascript

[pavansss91]

Code: [Select]

var od="";
var odc="";

function cal_ajax_date(d,m,y)
{
 if(d=="-")
  return false;
 else
 {
  var dt=y+"-"+m+"-"+d;
  calendardateajax(dt);
  if(od!="")
   document.getElementById(od).className=odc;
  odc=document.getElementById(dt).className;
  document.getElementById(dt).className="cal_select";
  od=dt;
  return true;
 }
}
What is the difference between first and below

Code: [Select]

var od="";
var odc="";

function cal_ajax_date(d,m,y)
{
 if(d=="-")
  return false;
 else
 {
  var dt=y+"-"+m+"-"+d;
  calendardateajax(dt);  //this is another function which displays a data using ajax.php
  if(od!="")
   document.getElementById(od).className=odc;
  alert(dt);
  odc=document.getElementById(dt).className;
  document.getElementById(dt).className="cal_select";
  od=dt;
  return true;
 }
}
Don't say alertbox. I am asking what is the other difference because when i have

Code: [Select]

<?php
$d=date("j",time());
$m=date("n",time());
$y=date("Y",time());

echo "
<script type=text/javascript>
window.onload=cal_ajax_date($d,$m,$y)
</script>";

?>

this in the main script i get

1st code: Error
                document.getElementById(dt) is null
                cal_ajax_date(1, 7, 2009)
                (?)()
                odc=document.getElementById(dt).className;

2nd code: It works fine as i wanted (actually i don't want the alertbox)

I don't understand where the mistake is
Somebody Help me Please

[Nox]

I'm not really sure, but judging from what you wrote about it - can't it be that the part after alert doesn't have to be availible immediately for the script and the alert creates a timeframe in which it can be made availible and allow the script to work properly?