data flow

strict unidirectional data flow

actions

actions are payloads of data

// Here’s an example action which
// represents adding a new todo item:

const ADD_TODO = 'ADD_TODO'
{
  type: ADD_TODO,
  text: 'Build my first Redux app'
}

reducers

reducers specify how the application’s state changes

const initialState = {
  visibilityFilter: VisibilityFilters.SHOW_ALL,
  todos: []
}

function todoApp(state = initialState, action) {
  switch (action.type) {
    case SET_VISIBILITY_FILTER:
      return Object.assign({}, state, {
        visibilityFilter: action.filter
      })
    default:
      return state
  }
}

store

the store is the object that brings actions and reducers together