function writeCookie(name, value, days){
    var expire = "";
    expire = new Date((new Date()).getTime() + days * 24 * 3600000);
    expire = "; expires=" + expire.toGMTString();
    document.cookie = name + "=" + escape(value) + expire;
}

var ww = document.getElementById('all').offsetWidth;
writeCookie('ww', ww, 1);