create-store.js

const createStore = (retucer) => {
	let state
	let listeners = []
	const getState = ()=> state
	const dispatch = (action)=>{
		state = reducer(state , action)
		listeners.forEach((listener) => listener() )
	}
	const subscribe = (listener)=>{
		listeners.push(listener);
		return ()=>{
			listeners.filter( (l)=> listener != l )
		}
	}
	state = dispatch({})
	return {
		getState , dispatch , subscribe
	}
}