It possible to allow browser cookie using Javascript?

I have seen before many website shows alert asking the user to accept or allow the browser cookies. Once the user click the alert's (banner) button, the browser accept the cookies. That is mean we can allow or accept the cookie using JavaScript. But after research, I conclude that we can't accept the cookies using JavaScript as answered here.

So how can I ask the user to allow the browser cookies by clicking a DOM button?

Thanks.