Javascript Date format(dateFormat)

 Date.prototype.format = function (dateFormat) {
    var day = this.getDate();
    var month = this.getMonth() + 1;
    var year = this.getFullYear();
    if (dateFormat === "dd/mm/yyyy")
    {/*from   www . j  a v a2  s. c o m*/
        return '{0}/{1}/{2}'.format(day, month > 9 ? month : '0' + month, year);
    }
};

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