define(['../lang/isDate'], function (isDate) {

    /**
     * return the day of the year (1..366)
     */
    function dayOfTheYear(date){
        return (Date.UTC(date.getFullYear(), date.getMonth(), date.getDate()) -
                Date.UTC(date.getFullYear(), 0, 1)) / 86400000 + 1;
    }

    return dayOfTheYear;

});