js时间计算加减

//方式1
Date.prototype.DateAdd = function(interval, number, date) {
    switch (interval) {
    case "y": {
        date.setFullYear(date.getFullYear() + number);
        return date;
        break;
    }
    case "m": {
        date.setMonth(date.getMonth() + number);
        return date;
        break;
    }
    case "w": {
        date.setDate(date.getDate() + number * 7);
        return date;
        break;
    }
    case "d": {
        date.setDate(date.getDate() + number);
        return date;
        break;
    }
    case "h ": {
        date.setHours(date.getHours() + number);
        return date;
        break;
    }
    case "m": {
        date.setMinutes(date.getMinutes() + number);
        return date;
        break;
    }
    case "s": {
        date.setSeconds(date.getSeconds() + number);
        return date;
        break;
    }
    }
}

//方式2
Date.prototype.DateAdd = function (strInterval, number) {
    //y年 q季度 m月 d日 w周 h小时 n分钟 s秒 ms毫秒
    var dtTmp = this;
    switch (strInterval) {
    case 's': return new Date(Date.parse(dtTmp) + (1000 * number));
    case 'n': return new Date(Date.parse(dtTmp) + (60000 * number));
    case 'h': return new Date(Date.parse(dtTmp) + (3600000 * number));
    case 'd': return new Date(Date.parse(dtTmp) + (86400000 * number));
    case 'w': return new Date(Date.parse(dtTmp) + ((86400000 * 7) * number));
    case 'q': return new Date(dtTmp.getFullYear(), (dtTmp.getMonth()) + number * 3, dtTmp.getDate(), dtTmp.getHours(), dtTmp.getMinutes(), dtTmp.getSeconds());
    case 'm': return new Date(dtTmp.getFullYear(), (dtTmp.getMonth()) + number, dtTmp.getDate(), dtTmp.getHours(), dtTmp.getMinutes(), dtTmp.getSeconds());
    case 'y': return new Date((dtTmp.getFullYear() + number), dtTmp.getMonth(), dtTmp.getDate(), dtTmp.getHours(), dtTmp.getMinutes(), dtTmp.getSeconds());
    }
};