01_basic.js

// http://jsbin.com/koyoduhito/1/edit?js,console,output

const counter = (state = 0, action) => {
  switch (action.type) {
    case 'INCREMENT':
      return state + 1;
    case 'DECREMENT':
      return state - 1;
    default:
      return state;
  }
}

const { createStore } = Redux;
const store = createStore(counter);

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

store.subscribe(render);
render();

document.addEventListener('click', () => {
    store.dispatch({
      type: 'INCREMENT'
    })
});