JS Commarization, Number to words from Million, Billion, Trillion.... and extendible

comma.js

function commarize()
{
	// 1e6 = 1 Million, begin with number to word after 1e6.
	if (this >= 1e6)
	{
		var units = 
		[
			"Million",
			"Billion",
			"Trillion",
			"Quadrillion",
			"Quintillion",
			"Sextillion",
			"Septillion",
			"Octillion"
			// ... Put others here, you can look them up here:
			// http://bmanolov.free.fr/numbers_names.php
			// If you prefer to automate the set of numbers, look at the number vocabulary:
			// https://gist.github.com/MartinMuzatko/1b468b7596c71e83838c
			// Javascript allows plain numbers to a maximum of ~1.79e308
		]

		// Divide to get SI Unit engineering style numbers (1e3,1e6,1e9, etc)
		var unit = Math.floor((this / 1000).toFixed(0).toString().length)
		// Calculate the remainder. 1,000,000 = 1.000 Mill
		var num = (this / ('1e'+(unit+2))).toFixed(3)
		var unitname = units[Math.floor(unit / 3) - 1]
		// output number remainder + unitname
		return num + ' ' + unitname
	}

	// Split floating number
	var parts = this.toString().split(".")
	// Only manipulate first part (not the float number)
	// If you prefer europe style numbers, you can replace . with ,
	parts[0] = parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",")
	return parts.join(".")
}

// Add method to prototype. this allows you to use this function on numbers and strings directly
Number.prototype.commarize = commarize
String.prototype.commarize = commarize

For the sake of history I leave this script here, but seriously. Use something like numeral.js to format numbers. :)