Adding commas to numbers

I could not find any good utils out there to add commas to numbers in JavaScript. So I wrote one:

	<script type="text/javascript">
	function comma(num) {
	var collector = new Array();
	var numberArray = ('' + num).split('').reverse();
	for(var i = 0; i < numberArray.length; i++) {
	if(i % 3 == 0 && i != 0) collector.push(",");
	collector.push(numberArray[i]);
	}
	return collector.reverse().join('');
	}
	</script>

view raw commify-javascript.js hosted with ❤ by GitHub

I found a Ruby example a long time ago, and it has served me well. Here is my Ruby comma util:

	class Numeric
	# Usage: 1234.commify # => '1,234'
	def commify
	self.to_s.reverse.scan(/(?:\d*\.)?\d{1,3}-?/).join(',').reverse
	end
	end

view raw commify-ruby.rb hosted with ❤ by GitHub

I love the Ruby version, but I am pretty proud of my JavaScript version as well.