JS比较时分秒时间的大小

    //hzp add 2009-5-15
    function chbaoliu(obj)
    {
      
      var now=new Date();
      var a=now.getFullYear() +"-" + now.getMonth() +"-" + now.getDate() +" "+obj.value+":00";
      var b=now.getFullYear() +"-" + now.getMonth() +"-" + now.getDate() +" " + now.getHours() +":" + now.getMinutes() +":" + now.getSeconds();
      
      if(CompareDate(a,b))
      {
         alert('不能选择以前时间！');obj.value="18:00";return false;
      }
      else
      {
       return true;
      }
      
    }
    
    function CompareDate(d1,d2)
    {
      return ((new Date(d1.replace(/-/g,"\/"))) < (new Date(d2.replace(/-/g,"\/"))));
   }