JavaScript sprintf function

jssprintf.js

/**
 * string.jssprintf function which acts like sprintf.
 *
 * Example
 *
 * 'Buy {0} get {1}'.jssprintf(5, 'one free');
 * which results in;
 * 'Buy 5 get one free'.
 */
(function () {
	'use strict';

	if (!String.prototype.jssprintf) {
		String.prototype.jssprintf = function() {
			var args = arguments;
			return this.replace(/{(\d+)}/g, function(match, number) {
				return args[number] !== undefined ? args[number] : match;
			});
		};
	}
}());