jQuery 获取本周、本月、本季度、本年的第一天和最后一天

function cxDate(btn){
    var nowDate = new Date();
    var beginDate = null;
    var endDate = null;
    if(btn == 1){//本日
        beginDate = nowDate.getFullYear() + "-" + (nowDate.getMonth()+1) + "-" + nowDate.getDate() + ' 00:00';
        endDate = myformatter(new Date());
    }else if(btn == 2){//本周
        nowDate.setDate(nowDate.getDate() - nowDate.getDay()+1);
        beginDate = nowDate.getFullYear() + "-" + (nowDate.getMonth()+1) + "-" + nowDate.getDate() + " 00:00";
        nowDate.setDate(nowDate.getDate() + 6);
        endDate = nowDate.getFullYear() + "-" + (nowDate.getMonth()+1) + "-" + nowDate.getDate() + " 23:59";
    }else if(btn == 3){//本月
        beginDate = nowDate.getFullYear() + "-" + (nowDate.getMonth()+1) + "-01 00:00";
        var day = new Date(nowDate.getFullYear(), nowDate.getMonth()+1, 0);
        endDate = nowDate.getFullYear() + "-" + (nowDate.getMonth()+1) + "-" + day.getDate() + " 23:59";
    }else if(btn == 4){//本季
        if(now.getMonth()+1 <= 3){
            beginDate = nowDate.getFullYear() + "-01-01 00:00";
            endDate = nowDate.getFullYear() + "-03-31 23:59";
        }else if(now.getMonth()+1 > 3 && now.getMonth()+1 <= 6){
            beginDate = nowDate.getFullYear() + "-04-01 00:00";
            endDate = nowDate.getFullYear() + "-06-30 23:59";
        }else if(now.getMonth()+1 > 6 && now.getMonth()+1 <= 9){
            beginDate = nowDate.getFullYear() + "-07-01 00:00";
            endDate = nowDate.getFullYear() + "-09-30 23:59";
        }else if(now.getMonth()+1 > 9 && now.getMonth()+1 <= 12){
            beginDate = nowDate.getFullYear() + "-10-01 00:00";
            endDate = nowDate.getFullYear() + "-12-31 23:59";
        }
    }else if(btn == 5){//本年
        beginDate = nowDate.getFullYear() + "-01-01 00:00";
        var day = new Date(nowDate.getFullYear(), 12, 0);
        endDate = nowDate.getFullYear() + "-12-" + day.getDate() + " 23:59";
    }
}