feat: improve performance by using Map instead of object

[qkreltms]

Is your feature request related to a problem? Please describe. You can improve performance by using Map instead of object when adding, reading listeners.

cnt	100				1000				100000
type	Map		Object		Map		Object		Map		Object
func	set	read	set	read	set	read	set	read	set	read	set	read
score(ms)	0.67	0.38	0.69	0.44	2.47	0.89	3.78	1.19	228	39	374	179
	0.5	0.4	0.76	0.47	2.44	0.34	3.82	1.22	247	37	371	151
	0.51	0.37	0.69	0.43	2.43	0.94	3.82	1.52	238	47	342	147
	0.54	0.41	0.71	0.42	3.76	0.88	4.13	1.18	234	50	354	150
	0.62	0.38	0.73	0.45	2.53	0.84	3.84	1.16	253	48	369	142
avg(ms)	0.56	0.38	0.71	0.44	2.72	0.77	3.87	1.25	240	44.2	362	153.8

Test scripts

Object

test('performance', () =>{
    const listenMiddleware = createMiddleware();

    let cnt = 0;
    console.time()
    for (let i=0;i<100;i++) {
      listenMiddleware.addListener('TEST', () => {
        cnt += 1;
      });
    }
    console.timeEnd()
    console.time()
    const middleware = listenMiddleware(mockStore)(mockNext);
    middleware({ type: 'TEST' });
    console.timeEnd()
    expect(Object.keys(listenMiddleware.listeners).length).toBe(100);
    expect(cnt).toBe(100);
})

Map

test('performance', () => {
  const listenMiddleware = createMiddleware();

  let cnt = 0;
  let t0 = performance.now()
  for (let i=0;i<100;i++) {
    listenMiddleware.addListener('TEST', () => {
      cnt += 1;
    });
  }
  let t1 = performance.now()
  console.log(t1-t0)
  t0 = performance.now()
  const middleware = listenMiddleware(mockStore)(mockNext);
  middleware({ type: 'TEST' });
  t1 = performance.now()
  console.log(t1-t0)
  expect(listenMiddleware.listeners.size).toBe(100);
  expect(cnt).toBe(100);
});