以前写的代码，写得比较简单。这里贴一下，我觉得可以作为演示JavaScript操作cookie用:)

效果看这里，完整代码（代码中的CookieManager拷贝自O'Reilly的《JavaScript & DHTML Cookbook》，Utility.each函数拷贝自jQuery中的each）在这里。

下面是关键的代码部分：

var PlayList = {
    cookieName:'PlayListIds',
    //保存要播放的视频id列表
    ids:[],
    //过期时间 单位秒
    expires:30,
    //读取cookie保存的播放列表信息 播放id保存格式为1232.1221.213.123  以.间隔
    read:function(){
        var cookieString = CookieManager.get(this.cookieName);
        return cookieString != '' ? cookieString.split('.') : [];
    },
    //获取视频id在数组中的索引
    indexOf:function(id){
        for(var i =0 ; i < this.ids.length; i++)
            if(this.ids[i] == id.toString())
                return i;
        return -1;
    },
    //更新cookie信息
    update:function(){
        CookieManager.set(
            this.cookieName,
            this.ids.join('.'),
            CookieManager.getExpiresDate(0,0,this.expires),
            '/',
            '.abc.com'
        );
    },
    //增加视频
    add:function(id){
        if(typeof id != "number" || this.indexOf(id) != -1) return;
        this.ids.push(id.toString());
        this.update();
    },
    //移除视频
    remove:function(id){
        var index = -1;
        if(typeof id != "number" || (index = this.indexOf(id)) == -1) return;
        this.ids.splice(index,1);
        this.update();
    },
    //清空列表
    clear:function(){
        CookieManager.clear();
        var pItem = null,pItemSel = null;
        for(var i = 0; i < this.ids.length; i++){
            if( (pItemSel = $('playlist-item-sel-'+this.ids[i])) != null
                && (pItem = $('playlist-item-'+this.ids[i])) != null )
            {
                pItemSel.className = "unselected";
                pItemSel.title = "添加到点播单";
                pItem.getElementsByTagName("img")[0].style.border = "5px solid white";
            }
        }
    },
    //渲染
    renderSelected:function(){
        var pItem = null,pItemSel = null;
        for(var i = 0; i < this.ids.length; i++){
            if( (pItemSel = $('playlist-item-sel-'+this.ids[i])) != null
                && (pItem = $('playlist-item-'+this.ids[i])) != null )
            {
                pItemSel.className = "selected";
                pItemSel.title = "从点播单移除";
                pItem.getElementsByTagName("img")[0].style.border = "5px solid yellow";
            }
        }
    },
    //处理点击
    toggle:function(el){
        if(el.className == 'unselected'){
            el.className = 'selected';
            el.title = "从点播单移除";
            el.parentNode.getElementsByTagName("img")[0].style.border = "5px solid yellow";
            this.add(parseInt(el.getAttribute('sid')));
        } else {
            el.className = 'unselected';
            el.title = "添加到点播单";
            el.parentNode.getElementsByTagName("img")[0].style.border = "5px solid white";
            this.remove(parseInt(el.getAttribute('sid')));
        }
    },
    //绑定事件
    attachEvent:function(){
        var _ = this;
        var els = Utility.getElementsByClassName("playlist","a","unselected");
        els = els.concat(Utility.getElementsByClassName("playlist","a","selected"));
        Utility.each(els,function(i,el){
            Utility.bind(el,'click',_.toggle,_,el)
        })
    },
    //初始化
    init:function(){
        this.ids = this.read();
        this.renderSelected();
        this.attachEvent();
    }
}