Reading existing cookies
Cookies for a given host, represented as nsICookie2 objects, can be enumerated as such:
let enum = Services.cookies.getCookiesFromHost("example.com");
while (enum.hasMoreElements()) {
var cookie = enum.getNext().QueryInterface(Ci.nsICookie2);
dump(cookie.host + ";" + cookie.name + "=" + cookie.value + "\n");
}
All cookies, regardless of host, can be enumerated using Services.cookies.enumerator rather than getCookiesFromHost().
Setting a cookie
The following code demonstrates how to set a cookie in Firefox.
Services.cookies.add(".host.example.com", "/cookie-path", "cookie_name", "cookie_value", is_secure, is_http_only, is_session, expiry_date);