cookie设置、获取、删除

var cookie={
    set: function(name, value, expires, path, domain){
        if(!expires){
            expires = -1;
        }
        if(!path){
            path = "/";
        }
        var d = "" + name + "=" + value;
        var e;
        if(expires < 0){
            e = "";
        }else if(expires == 0){
            var f = new Date(1970, 1, 1);
            e = ";expires=" + f.toUTCString();
        }else{
            var now = new Date();
            var f = new Date(now.getTime() + expires * 1000);
            e = ";expires=" + f.toUTCString();
        }
        var dm;
        if(!domain){
            dm = "";
        }else{
            dm = ";domain=" + domain;
        }
        
        document.cookie = name + "=" + escape(value) + ";path=" + path + e + dm;
    }, 

    get: function(name){
        var nameEQ = name + "=";
        var ca = document.cookie.split(';');
        for(var i = 0; i < ca.length; i++){
            var c = ca[i];
            while(c.charAt(0) == ' '){
                c = c.substring(1, c.length);
            }
            if(c.indexOf(nameEQ) == 0){
                return decodeURIComponent(c.substring(nameEQ.length, c.length))
            }
        }

        return null;
    },

    del: function(name){
        this.set(name, "", -1);
    }
};