javascript自定义日期函数

var DateFormat = function (date) {
    if (!(date instanceof Date)) {
        date = date.replace(/-/g, "/");
        date = new Date(date);
    }
    var month = date.getMonth() + 1;
    var year = date.getFullYear();
    var day = date.getDate();

    if (month < 10) {
        month = "0" + month;
    }
    if (day < 10) {
        day = "0" + day;
    }
    return year + "-" + month + "-" + day;
}

function DateAdd(type, number, date) {
    /*
      *   功能:实现JavaScript的DateAdd功能.
      *   参数:type,字符串表达式，表示要添加的时间间隔.
      *   参数:number,数值表达式，表示要添加的时间间隔的个数.
      *   参数:date,时间对象.
      *   返回:新的时间对象.
      *   var   OldDate   =   new   Date();
      *   var   newDate   =   DateAdd( "d",7,OldDate);
      */
    //d = new Date();
    if (!(date instanceof Date)) {
        date = date.replace(/-/g, "/");
        date = new Date(date);
    }
    switch (type) {
        case "y":
            date.setFullYear(date.getFullYear() + number);
            break;
        case "m":
            date.setMonth(date.getMonth() + number);
            break;
        case "w":
            date.setDate(date.getDate() + number * 7);
            break;
        case "d":
            date.setDate(date.getDate() + number);
            break;
        case "h":
            date.setHours(date.getHours() + number);
            break;
        case "m":
            date.setMinutes(date.getMinutes() + number);
            break;
        case "s":
            date.setSeconds(date.getSeconds() + number);
            break;
        default:
            date.setDate(d.getDate() + number);
            break;
    }
    return DateFormat(date);
}