Javascript: Add Leading Zero

Use this function to add leading zero in javascript:

function pad(n, width, z) {
  z = z || '0';
  n = n + '';
  return n.length >= width ? n : new Array(width - n.length + 1).join(z) + n;
}

Example usage:

pad(10, 4);      // 0010
pad(9, 4);       // 0009
pad(123, 4);     // 0123
pad(10, 4, '-'); // --10

credit : http://stackoverflow.com/a/10073788