What is the shortest function for reading a cookie by name in JavaScript?

Question

What is the shortest, accurate, and cross-browser compatible method for reading a cookie in JavaScript?

Very often, while building stand-alone scri

Answer 1

To have all cookies accessible by name in a Map:

const cookies = "a=b ; c = d ;e=";
const map = cookies.split(";").map((s) => s.split("=").map((s) => s.trim())).reduce((m, [k, v]) => (m.set(k, v), m), new Map());
console.log(map); //Map(3) {'a' => 'b', 'c' => 'd', 'e' => ''}
map.get("a"); //returns "b"
map.get("c"); //returns "d"
map.get("e"); //returns ""