cookies.js

function readCookies() {
  const cookies = document.cookie.replaceAll("; ", "&");
  const params = new URLSearchParams(cookies);
  return Object.fromEntries(params.entries());
}

cookies.ts

function readCookies(): Record<string, string> {
  const cookies = document.cookie.replaceAll("; ", "&");
  const params = new URLSearchParams(cookies);
  return Object.fromEntries(params.entries());
}

server.js

function readCookies(cookie) {
  const cookies = cookie.replaceAll("; ", "&");
  const params = new URLSearchParams(cookies);
  return Object.fromEntries(params.entries());
}

Oneliner:

Object.fromEntries(new URLSearchParams(document.cookie.replaceAll("; ", "&")).entries())