How can I format an integer to a specific length in javascript?

Question

I have a number in Javascript, that I know is less than 10000 and also non-negative. I want to display it as a four-digit number, with leading zeroes. Is there anything more e

Answer 1

A "while" loop should make this easy enough.

function formatLength(a) {
    var num = document.getElementById(a)
    while (num.value.length < 4) {
        num.value = '0' + num.value
    }
}

That would loop through until the length of the num value reached 4 digits (assuming you have passed in the id of the number element as an argument)