JavaScript - Crear cookie que expira en unos segundos

var d = new Date();

d.setTime(d.getTime() + (5 * 1000));

var expires = "expires="+ d.toUTCString();

document.cookie = 'f4_cl=1; expires; path=/';

function crearCookie(nombre, value) {

   var date = new Date();

   date.setTime(date.getTime()+(5*1000));

   var expires = "; expires="+date.toGMTString();

   document.cookie = nombre+"="+value+expires+"; path=/";

}