【www.bbyears.com--浏览器】
cookie是存于用户硬盘的一个文件,这个文件通常对应于一个域名,当浏览器再次访问这个域名时,便使这个cookie可用。因此,cookie可以跨越一个域名下的多个网页,但不能跨越多个域名使用。
不同的浏览器对cookie的实现也不一样,但其性质是相同的。例如在Windows 2000以及Windows xp中,cookie文件存储于documents and settingsuserNamecookie文件夹下。通常的命名格式为:userName@domain.txt。
cookie机制将信息存储于用户硬盘,因此可以作为全局变量
代码如下/*
*设置与获取Cookie
*/
var Cookie = {}
//写入Cookie,key为键,value是值
//duration过期时间(天为单位,默认1天)
Cookie.write = function (key, value, duration)
{
Cookie.remove(key);
var d = new Date();
if (duration <= 0)
duration = 1;
d.setTime(d.getTime() + 1000 * 60 * 60 * 24 * duration);
document.cookie = key + "=" + encodeURI(value) + "; expires=" + d.toGMTString() + ";path=/";
};
//移除Cookie,key为键
Cookie.remove = function (key)
{
var d = new Date();
if (Cookie.read(key) != "")
{
d.setTime(d.getTime() - (86400 * 1000 * 1));
document.cookie = key + "=;expires=" + d.toGMTString();
}
};
//读取Cookie,key是键
//不存在返回空字符串""
Cookie.read = function (key)
{
var arr = document.cookie.match(new RegExp("(^| )" + key + "=([^;]*)(;|$)"));
if (arr != null)
return decodeURIComponent(arr[2]);
return "";
};
实例
要用到2个js文件,history.js,关键的聊天记录保存和读取代码。json.js,对json进行处理。
代码如下var addHistory=function(num,id){
stringCookie=getCookie("history");
var stringHistory=""!=stringCookie?stringCookie:"{history:[]}";
var json=new JSON(stringHistory);
var e="{num:"+num+",id:"+id+"}";
json["history"].push(e);//添加一个新的记录
setCookie("history",json.toString(),30);
}
//显示历史记录
var DisplayHistory=function(){
var p_ele=document.getElementById("history");
while (p_ele.firstChild) {
p_ele.removeChild(p_ele.firstChild);
}
var historyJSON=getCookie("history");
var json=new JSON(historyJSON);
var displayNum=6;
for(i=json["history"].length-1;i>0;i--){
addLi(json["history"][i]["num"],json["history"][i]["id"],"history");
displayNum--;
if(displayNum==0){break;}
}
}
//添加一个li元素
var addLi=function(num,id,pid){
var a=document.createElement("a");
var href="product.action?pid="+id;
a.setAttribute("href",href);
var t=document.createTextNode(num);
a.appendChild(t);
var li=document.createElement("li");
li.appendChild(a);
document.getElementById(pid).appendChild(li);
}
//添加cookie
var setCookie=function(c_name,value,expiredays)
{
var exdate=new Date()
exdate.setDate(exdate.getDate()+expiredays)
cookieVal=c_name+ "=" +escape(value)+((expiredays==null) ? "" : ";expires="+exdate.toGMTString());
// alert(cookieVal);
document.cookie=cookieVal;
}
//获取cookie
function getCookie(c_name)
{
if (document.cookie.length>0)
{
c_start=document.cookie.indexOf(c_name + "=")
if (c_start!=-1)
{
c_start=c_start + c_name.length+1
c_end=document.cookie.indexOf(";",c_start)
if (c_end==-1) c_end=document.cookie.length
// document.write(document.cookie.substring(c_start,c_end)+"
");
return unescape(document.cookie.substring(c_start,c_end))
}
}
return ""
}
json数据如下
代码如下 var JSON = function(sJSON){this.objType = (typeof sJSON);
this.self = [];
(function(s,o){for(var i in o){o.hasOwnProperty(i)&&(s[i]=o[i],s.self[i]=o[i])};})(this,(this.objType=="string")?eval("0,"+sJSON):sJSON);
}
JSON.prototype = {
toString:function(){
return this.getString();
},
valueOf:function(){
return this.getString();
},
getString:function(){
var sA = [];
(function(o){
var oo = null;
sA.push("{");
for(var i in o){
if(o.hasOwnProperty(i) && i!="prototype"){
oo = o[i];
if(oo instanceof Array){
sA.push(i+":[");
for(var b in oo){
if(oo.hasOwnProperty(b) && b!="prototype"){
sA.push(oo[b]+",");
if(typeof oo[b]=="object") arguments.callee(oo[b]);
}
}
sA.push("],");
continue;
}else{
sA.push(i+":"+oo+",");
}
if(typeof oo=="object") arguments.callee(oo);
}
}
sA.push("},");
})(this.self);
return sA.slice(0).join("").replace(/[object object],/ig,"").replace(/,}/g,"}").replace(/,]/g,"]").slice(0,-1);
},
push:function(sName,sValue){
this.self[sName] = sValue;
this[sName] = sValue;
}
}
html代码
代码如下<script type="text/javascript" src="../js/json.js"></script>
<script type="text/javascript" src="../js/history.js"></script>
<script>
addHistory(15810782304,2);
addHistory(64654665,2);
addHistory(6843212,2);
addHistory(84984432521,2);
setInterval("DisplayHistory()",1000);
</script>