js判断开始时间不能小于结束时间

function validTime(startTime,endTime){

       var arr1 = startTime.split("-");
       var arr2 = endTime.split("-");
       var date1=new Date(parseInt(arr1[0]),parseInt(arr1[1])-1,parseInt(arr1[2]),0,0,0); 
       var date2=new Date(parseInt(arr2[0]),parseInt(arr2[1])-1,parseInt(arr2[2]),0,0,0);
       if(date1.getTime()>date2.getTime()) {                                
               alert('结束日期不能小于开始日期',this);
               return false;
         }else{
             return true;
         }
         return false;

}