获取上个月在昨天这一天的日期

//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;
    }
    var datastr = strYear + "-" + strMonth + "-" + strDay;
    return datastr;
}