js获取昨天的日期

function getYestoday(){    
   var date = new Date();
      var yesterday_milliseconds=date.getTime()-1000*60*60*24;          
      var yesterday = new Date();          
         yesterday.setTime(yesterday_milliseconds);          
            
      var strYear = yesterday.getFullYear();       
      var strDay = yesterday.getDate();       
      var strMonth = yesterday.getMonth()+1;     
      if(strMonth<10){       
         strMonth="0"+strMonth;       
      }       
      datastr = strYear+"-"+strMonth+"-"+strDay;     
      return datastr;     
  }