Dynamic input form field elements, works IE not FF

I've been looking for a javascript like this example: http://javascript.internet.com/forms/dynamic-input.html

Here you can fill in (in this example) a number of URLS, then this script adds a number of fields as put in in the box.

The example works in internet explorer but not in firefox.

Does anybody has experience to make this cross-browser compatible? Or does anybody has maby another example with doing this?

Thanks in advance!

 

I've updated the createForm function so it's a bit more standards friendly for you. (Works in IE + FF now)

function createForm(number) {
data = "";    
inter = "'";
if (number < 16 && number > -1) {
for (i=1; i <= number; i++) {
if (i < 10) spaces="&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;";
else spaces="&nbsp;&nbsp;&nbsp;&nbsp;";
data = data + "URL " + i + " :" + spaces
+ "<input type='text' size=10 name=" + inter
+ "url" + i + inter + "'><br>";
}
document.getElementById("cust").innerHTML = data;
}
else {
window.alert("Please select up to 15 entries.");
   }
}

Code (markup):

 

Thanks! Appreciate your input

 

No problem mate!