js获取当前日期的前一天、一月、一年的日期 明天、后天(转)

function getYestoday(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;
  }

  //获得上个月在昨天这一天的日期
  function getLastMonthYestdy(date){
     var daysInMonth = new Array([0],[31],[28],[31],[30],[31],[30],[31],[31],[30],[31],[30],[31]);
     var strYear = date.getFullYear();
     var strDay = date.getDate();
     var strMonth = date.getMonth()+1;
     if(strYear%4 == 0 && strYear%100 != 0){
        daysInMonth[2] = 29;
     }
     if(strMonth - 1 == 0)
     {
        strYear -= 1;
        strMonth = 12;
     }
     else
     {
        strMonth -= 1;
     }
     strDay = daysInMonth[strMonth] >= strDay ? strDay : daysInMonth[strMonth];
     if(strMonth<10)
     {
        strMonth="0"+strMonth;
     }
     if(strDay<10)
     {
        strDay="0"+strDay;
     }
     datastr = strYear+"-"+strMonth+"-"+strDay;
     return datastr;
  }

  //获得上一年在昨天这一天的日期
  function getLastYearYestdy(date){
     var strYear = date.getFullYear() - 1;
     var strDay = date.getDate();
     var strMonth = date.getMonth()+1;
     if(strMonth<10)
     {
        strMonth="0"+strMonth;
     }
     if(strDay<10)
     {
        strDay="0"+strDay;
     }
     datastr = strYear+"-"+strMonth+"-"+strDay;
     return datastr;
  }