js获取上周上个月的时间

    //获取系统当前时间  
    var nowdate = new Date();
    var y = nowdate.getFullYear();
    var m = nowdate.getMonth()+1;
    var d = nowdate.getDate();
    var formatnowdate = y+'-'+m+'-'+d;
    console.log(formatnowdate)
    //获取系统前一周的时间
    var oneweekdate = new Date(nowdate-30*24*3600*1000);
    var y = oneweekdate.getFullYear();
    var m = oneweekdate.getMonth()+1;
    var d = oneweekdate.getDate();
    var formatwdate = y+'-'+m+'-'+d;
    console.log(formatwdate)
    //获取系统前一个月的时间
    nowdate.setMonth(nowdate.getMonth()-1);
    var y = nowdate.getFullYear();
    var m = nowdate.getMonth()+1;
    var d = nowdate.getDate();
    var formatwdate = y+'-'+m+'-'+d;
    console.log(formatwdate)