const wm = new WeakMap();
const obj1 = { name: 'Sarah' };
const obj2 = { name: 'Mike' };

wm.set(obj1, 'developer');
wm.set(obj2, 'designer');

console.log(wm.get(obj1));
console.log(wm.has(obj2));
console.log(wm.get({ name: 'Sarah' }));
console.log(wm.delete(obj1));
console.log(wm.has(obj1));