A very (read: don't do this) simple implementation of redux

simple-redux.js

/*
* The reason for this is just a thought exercise
* often people(myself super included) are so confused
* when trying something new, but breaking it down
* to it's simplest existence can be the best way to understand
*/
function createStore(reducer, initState) {
	let state = initState;
	let subscribers = [];

	const getState = () => state;
	const dispatch = (action) => {
		state = reducer(state, action);
		subscribers.forEach((subscriber) => subscriber());
		return action;
	}
	const subscribe = (listener) => {
		subscribers.push(listener);
		return () => {
			subscribers = subscribers.slice(subscribers.indexOf(listener) + 1, 1);
		};
	}
	return {
		dispatch,
		subscribe,
		getState
	}
}

const initState = {
	name: "Conor",
	redux: "awesome"
};
const myReducer = (state, action) => {
	let newState = Object.assign({}, state);
	switch (action.type) {
		case "CHANGE_NAME":
			newState.name = action.name;
			break;
		case "CHANGE_REDUX_ADJECTIVE":
			newState.redux = action.adjective;
			break;
		default: 
			//do nothing
	}
	return newState
};

const store = createStore(myReducer, initState);

console.log(store.getState(), "initial state");

const subscriber = store.subscribe(() => {
	console.log("i'll console state changes twice then unsubscribe so you will not be notified of the third dispatch", store.getState());
});

store.dispatch({
	type: "CHANGE_NAME",
	name: "Conor Hastings"
});

store.dispatch({
	type: "CHANGE_REDUX_ADJECTIVE",
	adjective: "great"
});

subscriber();

store.dispatch({
	type: "CHANGE_NAME",
	name: "Conor Cool Guy"
});

console.log("the state changed but since we unsubscribed the listener above was not notified o the final dispatch", store.getState());