Cookies may be used for switching display languages and A/B tests.
By using a [JS Step], you can set the cookie value as follows:
document.cookie = 'cookie_name=cookie_parameter';
document.cookie = 'lang=en'; /* Common language settings */
If you want to delete the cookies that have been set, it's possible with the following code:
document.cookie = 'cookie_name=; max-age=0';
A cookie with the HttpOnly attribute
A cookie with the HttpOnly attribute can't be accessed by JavaScript, so you cannot set or delete them using a JS Step.