js获取上个月日期

javascript根据当前日期获取上个月日期

function lastMonthDate(){
    var Nowdate = new Date();
    var vYear = Nowdate.getFullYear();
    var vMon = Nowdate.getMonth() + 1;
    var vDay = Nowdate.getDate();
　　//每个月的最后一天日期（为了使用月份便于查找，数组第一位设为0）
    var daysInMonth = new Array(0,31,28,31,30,31,30,31,31,30,31,30,31);
    if(vMon==1){
        vYear = Nowdate.getFullYear()-1;
        vMon = 12;
    }else{
        vMon = vMon -1;
    }
　　//若是闰年，二月最后一天是29号
    if(vYear%4 == 0 && vYear%100 != 0  || vYear%400 = 0 ){
        daysInMonth[2]= 29;
    }
    if(daysInMonth[vMon] < vDay){
        vDay = daysInMonth[vMon];
    }
    if(vDay<10){
        vDay="0"+vDay;
    }
    if(vMon<10){
        vMon="0"+vMon;
    }
    var date =vYear+"-"+ vMon +"-"+vDay;
    console.log(date)
    return date;
}