//取得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 "";
}

//清除cookie    
function clearcookie(name) {
    setcookie(name, "", -1);
}

//设置cookie    
function setcookie(name, value, seconds) {
    seconds = seconds || 0;   //seconds有值就直接赋值，没有为0，这个根php不一样。    
    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    
}