redux笔记

Introduction

Motivation

http://redux.js.org/docs/introduction/Motivation.html

Mutation & Asynchronicity

Solving by imposing certain restrictions -- Principles

Principles

http://redux.js.org/docs/introduction/ThreePrinciples.html

Single source of truth

The state of your whole application is stored in an object tree within asingle
store

State is read-only

the only way to mutate the state is to emit an action, an objectdescribe what happened

Changes are made with pure functions

to specify how the state tree is transformed by actions, you write purereducers

Basics

Actions

http://redux.js.org/docs/basics/Actions.html
http://redux.js.org/docs/recipes/ReducingBoilerplate.html
actions are payloads of information that send data from your application to your store. 

define action type:

const ADD_TODO = 'ADD_TODO';

action object:

{

  type: ADD_TODO,

  payload: {

    text: "this is todo text"

  }

}

action creators:

action creators are exactly that -- functions that create actions

function addTodo(text) {

  return {

    type: ADD_TODO,

    payload: {

      text: text

    }

  };

}

async actions

Reducers

Actions describe something happened, but don't specify how the application's state changes in response. This is the job of a reducer.

design the state shape

{ todos: [ ... ], .... }

handling actions

(previousState, action) => newState

initialState = { todos: [] };

function todoApp (state = initialState, action) {

  switch (action.type) {

    case ADD_TODO: 

      return Object.assign({}, state, {

        todos: [

          ...state.todos,

          {

            text: action.payload.text

          }

        ]

      });

    default:

      return state;

  }

}

split reducers / handle more actions

Store

http://redux.js.org/docs/basics/Store.html

responsibilities:

1. holds application state (from reducer)

2. allows access state via store.getState()

3. allows state to be updated via store.dispatch(action) 

4. store.subscribe(listener)

5. unsubscribe

import { createStore } from 'redux'

import todoApp from './reducers'

let store = createStore(todoApp)

let unsubscribe = store.subscribe(() => console.log('state changed'));

unsubscribe();

Data Flow

Advanced

Async Actions

ajax call