printf JavaScript

printf.js

if (!String.format) {
    /**
     * printf function
     * @link http://stackoverflow.com/questions/610406/javascript-equivalent-to-printf-string-format
     * @example var fullName = String.format('{0} {1}', firstName, lastName);
     * 
     * @param {string} format String with replacable parameters
     * @returns {string} formatted string
     */
    String.format = function(format) {
        var args = Array.prototype.slice.call(arguments, 1);
        return format.replace(/{(\d+)}/g, function(match, number) { 
            return typeof args[number] != 'undefined' ? args[number] : match;
        });
    };
}