JS Bin Reducer-example // source https://jsbin.com/mirenat

<!DOCTYPE html>
<html>
<head>
<meta name="description" content="Reducer-example">
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>
  
  <script src="https://unpkg.com/expect/umd/expect.min.js"></script>
  <script src="https://fb.me/react-0.14.0.min.js"></script>
  <script src="https://fb.me/react-dom-0.14.0.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/redux/3.0.4/redux.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/react-redux/4.0.0/react-redux.min.js"></script>
<script id="jsbin-javascript">
'use strict';

var counter = function counter(state, action) {
  if (state === undefined) state = 0;

switch (action.type) {
    case 'INCREMENT':
      return state + 1;
      break;
    case 'DECREMENT':
      return state - 1;
      break;
    default:
      return state;
      break;
  }
};

var _Redux = Redux;
var createStore = _Redux.createStore;

var store = createStore(counter); // create store with a reducer of counter

// console.log(store.getState());

var render = function render() {
  document.body.innerText = store.getState();
};

store.subscribe(render);
render();

document.addEventListener('click', function () {
  store.dispatch({ type: 'INCREMENT' });
});
</script>

const { createStore } = Redux;
const store = createStore(counter); // create store with a reducer of counter

// console.log(store.getState());

const render = () => {
  document.body.innerText = store.getState();
}

store.subscribe(render)
render()

document.addEventListener('click', () => {
  store.dispatch({ type: 'INCREMENT'})
})</script></body>
</html>

https://unpkg.com/expect/umd/expect.min.js

https://fb.me/react-0.14.0.min.js

https://fb.me/react-dom-0.14.0.min.js

https://cdnjs.cloudflare.com/ajax/libs/redux/3.0.4/redux.min.js

https://cdnjs.cloudflare.com/ajax/libs/react-redux/4.0.0/react-redux.min.js