Simple JS Observer pattern

observer.js

let store = {
  nextId: 1,
  cache: {},
  add(fn) {
    if(!fn.id) {
      fn.id = this.nextId++;
      this.cache[fn.id] = fn;
    }
    return false;
  },
  runAll() {
    for (let i=1; i < this.nextId; i++) {
      this.cache[i]();
    }
  }
}

let func = () => console.log('test')
store.add(func)
store.add(func) // will not be re-added
store.add(() => console.log('test 2'))
store.run()