cookie

//设置cookie  
function setCookie(name, value, seconds) {  
     seconds = seconds || 0;   //seconds有值就直接赋值，没有为0.  
     var expires = "";  
     if (seconds != 0 ) {      //设置cookie生存时间  
         var date = new Date();  
         date.setTime(date.getTime()+(seconds*1000));  
         expires = "; expires="+date.toGMTString();  
     }  
     document.cookie = name+"="+escape(value)+expires+"; path=/";   //转码并赋值  
}  

//获取cookie  
function getCookie(name) {  
    var nameEQ = name + "=";  
    var ca = document.cookie.split(';');    //把cookie分割成组  
    for(var i=0;i < ca.length;i++) {  
       var c = ca[i];                      //取得字符串  
       while (c.charAt(0)==' ') {          //判断一下字符串有没有前导空格  
          c = c.substring(1,c.length);      //有的话，从第二位开始取  
       }  
       if (c.indexOf(nameEQ) == 0) {       //如果含有我们要的name  
          return unescape(c.substring(nameEQ.length,c.length));    //解码并截取我们要值  
       }  
    }  
    return false;  
}  


//清除cookie  
function clearCookie(name) {  
    setCookie(name, "", -1);  
}  


setCookie("test","haha",1800);         //设置cookie的值，生存时间半个小时  
alert(getCookie('test'));                     //取得cookie的值，显示haha
clearCookie("test");                           //删除cookie的值  
alert(getCookie('test'));                     //test对应的cookie值为空，显示为false.就是getCookie最后返的false值。