Format number with leading zeros

format-number.js

// relatively safe
function formatSafely(num, digits) {
    return (Array(digits).join('0') + Math.floor(num)).substr(-digits);
}

// or quick
function formatQuickly(num, digits) {
    return (Array(digits).join('0') + num).substr(-digits);
}

// or inline
var formatted = ('00' + 7).substr(-3);