res.cookie()Sets a cookie with name (name) and value (value) to be sent along with the response.
res.cookie(name, value [,options]);
The path option defaults to "/".
maxAge is a convenience option that sets expires relative to the current time in milliseconds. 
res.cookie('rememberme', '1', { maxAge: 900000, httpOnly: true });
An object that is passed is then serialized as JSON, which is automatically parsed by the Express body-parser middleware.
res.cookie('cart', { items: [1,2,3] });
res.cookie('cart', { items: [1,2,3] }, { maxAge: 900000 });
Signed cookies are also supported through this method—just pass the signed option, set to true. res.cookie() will then use the secret passed into express.cookieParser(secret) to sign the value.
res.cookie('name', 'tobi', { signed: true });
res.cookie('name', 'tobi', {
  domain: '.example.com',
  path: '/admin',
  secure: true
});
res.cookie('rememberme', '1', {
  expires: new Date(Date.now() + 900000),
  httpOnly: true
});