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Shared, synchronous, independent state for javascript apps.

Basically re-implemented the Redux API without ES6 syntax and some of the top-level API exports.


  1. You're application state is hidden within the atom function. It cannot be mutated outside of the atom function.
  2. To affect your state, you need to trigger an "action".
  3. "actions" can be just a string, or an object or any value you want.
  4. You define a single "reducer" function that accepts the current state and action and returns a new state.
  5. You can register any # of "subscribers" that are called after your reducer returns a new state.


function counter(state, action) {
  switch (action.type) {
  case 'INCREMENT':
    return state + 1;
  case 'DECREMENT':
    return state - 1;
    return function(dispatch) {
      setTimeout(function() {
        dispatch({type: 'INCREMENT'});
      }, 1000);
    return state;
var store = atom(counter, 0);
store.subscribe(function() {
store.dispatch({ type: 'INCREMENT' }); // 1 
store.dispatch({ type: 'INCREMENT' }); // 2 
store.dispatch({ type: 'DECREMENT' }); // 1 
store.dispatch({ type: 'INCREMENT_ASYNC' }); // 2 

See also: Simple Routing Example


atom(reducer[, initialState])

Creates your atom store that contains your application state. Returns an Object with methods for interacting with your state.

reducer(state, action)

A function that accepts function(state, action) and returns the potentially modified state. You can also return a function with the signature function(dispatch) for performing asynchronous tasks before modifying the state. When your async task completes, the passed in dispatch function can be called with an "action" that results your reducer returning a new state.

Store API


This calls your "reducer" with the current state and the given "action".


Add a function to be called anytime after your "reducer" has returned a new state. This is useful for logging changes or syncing to your storage or database.

You can add as many listeners as you would like.


Returns the current state. Useful for calling within a subscribed listener.