Simple setting retriever from cookies
Since (I assume) there should only be a single cookie fragment called cookie_law you should use find instead of filter. filter will go through the whole array even if the result is the first element.
As it stands I think that it is bad for a filter method to modify the underlying data.
Also the number of parenthesis in the line
.map(c =&gt; JSON.parse(atob(decodeURIComponent(c.pop())))).pop()

is pretty scary. I would pull at least some of that out into another method.
update
In my code I usually split out my logic with a method to get any cookie, that way I can reuse it for other cookies. The logic also ends up being simpler.
function getCookieLawSettings() {
    return decodeCookie(getCookie('cookie_law'));
}

function getCookie(na,e) {
    var cookie = document.cookie.split(';')
            .map(c =&gt; c.trim().split('='))
            .filter(c =&gt; c[0] === name);
    return cookie ? cookie[1] : undefined;
}

function decodeCookie(data) {
    return JSON.parse(atob(decodeURIComponent(data)));
}

function encodeCookie(data) {
    return btoa(encodeURIComponent(JSON.stringify)));
}