Code
//By default, getTimezoneOffset returns the time zone offset in minutes
setCookie("timezone", new Date().getTimezoneOffset()/60);
function setCookie(name, value, expires, path, domain, secure)
{
document.cookie= name + "=" + escape(value) +
((expires) ? "; expires=" + expires.toGMTString() : "") +
((path) ? "; path=" + path : "") +
((domain) ? "; domain=" + domain : "") +
((secure) ? "; secure" : "");
}