js 日期比较

 function checkDay() {
      debugger;
     var confirmbytime = $('#confirmbytime').val();
     var today = new Date();
        var year=today.getFullYear();
        var month=today.getMonth()+1;
        var day=today.getDate();
        var d1=toDate(year + "-" + month + "-" + day);
        var d2=toDate(confirmbytime);
        alert("当前时间="+d1);
        alert("d2="+d2);
        alert(d1<d2);
     }
   
    function toDate(str){
        var sd=str.split("-");
        return new Date(sd[0],sd[1],sd[2]);
    }