谁能帮我解释下这段javascript的含义和作用，谢谢！

Question

 var Remember = new Object();
Remember = function(){};
Remember.prototype = {
    initialize: function(el, options){
        this.el = $(el);
        this.days = 365;
        this.options = options;
        this.effect();
        var cookie = this.readCookie();
        if (cookie) {
            this.fx.now = cookie;
            this.fx.increase();
        }
    },

    //cookie functions based on code by Peter-Paul Koch
    setCookie: function(value) {
        var date = new Date();
        date.setTime(date.getTime()+(this.days*24*60*60*1000));
        var expires = "; expires="+date.toGMTString();
        document.cookie = this.el+this.el.id+this.prefix+"="+value+expires+"; path=/";
    },

    readCookie: function() {
        var nameEQ = this.el+this.el.id+this.prefix + "=";
        var ca = document.cookie.split(';');
        for(var i=0;c=ca[i];i++) {
            while (c.charAt(0)==' ') c = c.substring(1,c.length);
            if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
        }
        return false;
    },

    custom: function(from, to){
        if (this.fx.now != to) {
            this.setCookie(to);
            this.fx.custom(from, to);
        }
    }
}

就是这段代码，看了半天没看明白，下面这3行，每行是什么意思呢？

 date.setTime(date.getTime()+(this.days*24*60*60*1000));
        var expires = "; expires="+date.toGMTString();
        document.cookie = this.el+this.el.id+this.prefix+"="+value+expires+"; path=/";

Answer 1

这三行代码用来设置过期时间，date.getTime()得到的当前时间，这个时间是一个整数，代表从某个时间段到现在的毫秒数。那么过期时间就是当前时间+天数*24*60*60*1000毫秒。
一天等于24小时，24*60分，24*60*60秒，24*60*60*1000毫秒。