Pad left class :-]

NuxPadder.js

/**
 * Pad class.
 * 
 * @author Maciej "Nux" Jaros
 * @license CC-BY
 * 
 * Note! The class becomes faster with new itterations.
 */
NuxPadder = function (character)
{
	if (typeof character !== 'string' || character.length < 1) {
		character = ' ';
	}
	this.paddingString = character;
}
/**
 * Prepare internals for given length
 */
NuxPadder.prototype.prepare = function (neededCharacters)
{
	if (this.paddingString.length >= neededCharacters) {
		return;
	}
	
	while (this.paddingString.length < neededCharacters) {
		this.paddingString += this.paddingString;
	}
}
/**
 * Pad left `str` to have at least `length` characters.
 */
NuxPadder.prototype.padLeft = function(str, length) {
	var neededCharacters = length - str.length;
	if (neededCharacters > 0) {
		this.prepare(neededCharacters);
	}
	return this.paddingString.substr(0, neededCharacters) + str;
}

usage.js

var pad = new NuxPadder(' ');
pad.padLeft('123', 1) // -> '123'
pad.padLeft('123', 3) // -> '123'
pad.padLeft('123', 5) // -> '  123'

// Note! If you know beforehand how much padding you will need use `prepare` function
var columns = ["abc", "def", "123456789"];
var columnWidths = [5, 5, 15];
var maxPad = 15;
var pad = new NuxPadder(' ');
pad.prepare(maxPad)
for (var i = 0; i < columns.length; i++) {
	columns[i] = pad.padLeft(columns[i], columnWidths[i]);
}

// columns = ["  abc", "  def", "      123456789"]