js 获取YYYY-MM-DD形式的今天日期和昨天日期

var newdate = null;
  function getToDay(){
   var now = new Date();
   var nowYear = now.getFullYear();
   var nowMonth = now.getMonth();
   var nowDate = now.getDate();
   newdate = new Date(nowYear,nowMonth,nowDate);
   nowMonth = doHandleMonth(nowMonth + 1);
   nowDate = doHandleMonth(nowDate);
   return nowYear+"-"+nowMonth+"-"+nowDate;
  }
  function doHandleMonth(month){
   if(month.toString().length == 1){
    month = "0" + month;
   }
   return month;
  }
  function getYesterDay(){
   var newtimems=newdate.getTime()-(24*60*60*1000);
   var yesd = new Date(newtimems);
   var yesYear = yesd.getFullYear();
   var yesMonth = yesd.getMonth();
   var yesDate = yesd.getDate();
   yesMonth = doHandleMonth(yesMonth + 1);
   yesDate = doHandleMonth(yesDate);
   return yesYear+"-"+yesMonth+"-"+yesDate;
  }
  alert("今天时间是:::" + getToDay());
  alert("昨天时间是:::" + getYesterDay());