Get Date value like (2015-29-19)

 var today = new Date(sdate);
    var mm = today.getMonth()
    var yyyy = today.getFullYear();
    var day = today.getDate();
    var monthStart = new Date(yyyy, mm, day);
    var firstday = monthStart.getFullYear() + "-" + (monthStart.getMonth() + 1) + "-" + monthStart.getDate();