Hi,
Here I write some code for your requirement check this once
<input type="text" name="data" id="data" style =" display :none;">
In the desing I take one html textbox
And javascript contains following code
var e = 0;
var tmp;
function f1() {
e = parseInt(e) + 1;
if (parseInt(e) == 30) {
document.getElementById("data").style.display = '';
}
tmp=setTimeout("f1()", 300);
}
And you've to add this f1 function in onload event of page like
<body onload ="f1()" >
That method counts the time
I hope this helps you
All the Best