//日期時間計算-當前日期前多少天
    function getBeforeDate(n) {
        var n = n;
        var d = new Date();
        var year = d.getFullYear();
        var mon = d.getMonth() + 1;
        var day = d.getDate();
        if (day < n) {
            if (mon > 1) {
                mon = mon - 1;
            }else{
                mon = 12;
            }
        }
        d.setDate(d.getDate - n);
        year = d.getFullYear();
        mon = d.getMonth() + 1;
        day = d.getDate();
        s = year + "-" + (mon < 10 ? ('0' + mon) : mon) + "-" + (day < 10 ? ('0' + day) : day);
        return s;
    }