Pad string with characters

function padString(length, StringToPad, PadStringWith) {

  var returnString = ""

  if (StringToPad.length < length) {

    for (var i = 0; i < length - 1; i++) {

      returnString += PadStringWith;

    }

  }

  returnString += StringToPad;

  return returnString;

}

Use it like this:

var strMonth = padString(2, "11", "0");