form validation help?

i have these to validation script that check to see if the input filed is blank or contains characters. i only want it to contain numbers

...value.charAt(i) = "") this part seems to wrong.

if (document.theForm.propid.value.charAt(i) = "") {
window.alert('Please enter only numbers in the property search field');
return false;
}
if (document.theForm.propid.value=="") {
window.alert ("Please Enter a Property ID!");
return false;
}

if (i==2) document.theForm.action=
"prop.php?page_from=all.php";
document.theForm.submit()

}

also this part "prop.php?page_from=all.php"; dosent seem to carry the ..?page_from=all.php

through to the prop.php page. why is that.

cheers aron.

Here is an absolute goldmine of validation functions: http://www.mattkruse.com/javascript/validations/

you can also try this product...you get 14 days with it and it will generate all the code for you.

http://www.javascript-coder.com/index.phtml

You simply create the form in HTML, then open the coder prog and select that form you just created.

Then you can select validation criteria on a number of constraints.

Just an idea, if you want to save time coding it.
cheers.