js 取 cookie 的中文乱码

//写入Cookie

$username="中文编码";
$username=mb_convert_encoding($username,"UTF-8","GB2312");  //因为 此文件为ascii 编码
//$username=iconv("GB2312","UTF-8",$username);

$username=urlencode($username);  //这个 函数出来的 结果 与 js cookie 

setcookie('testname',$username,time()+3600);

//读取
//document.write( document.cookie);

document.writeln(decodeURI("<?= $username ?>")) ;

document.writeln(GetCookie("testname")) ;

function GetCookie(cookieName){
    var cookieString = document.cookie;
    //return cookieString;
    var start = cookieString.indexOf(cookieName + '=');
    if (start == -1) 
	    return null;
    start += cookieName.length + 1;
    var end = cookieString.indexOf(";", start);
    if (end == -1) 
    return decodeURI(cookieString.substring(start));
    //return unescape(cookieString.substring(start));
    
    return decodeURI(cookieString.substring(start, end));
    //return unescape(cookieString.substring(start, end));
}

或者简单一点：
escape

decodeURIComponent

需要用decodeURIComponent函数对cookie读取的中文进行处理就可以了.

如：username = decodeURIComponent(escape(username));