redux react-redux

[wuye1200]

function createStore (reducer) {
  let state = null
  const listeners = []
  const subscribe = (listener) => listeners.push(listener)
  const getState = () => state
  const dispatch = (action) => {
    state = reducer(state, action)
    listeners.forEach((listener) => listener())
  }
  dispatch({}) // 初始化 state
  return { getState, dispatch, subscribe }
}

function renderApp (newAppState, oldAppState = {}) { // 防止 oldAppState 没有传入，所以加了默认参数 oldAppState = {}
  if (newAppState === oldAppState) return // 数据没有变化就不渲染了
  console.log('render app...')
  renderTitle(newAppState.title, oldAppState.title)
  renderContent(newAppState.content, oldAppState.content)
}

function renderTitle (newTitle, oldTitle = {}) {
  if (newTitle === oldTitle) return // 数据没有变化就不渲染了
  console.log('render title...')
  const titleDOM = document.getElementById('title')
  titleDOM.innerHTML = newTitle.text
  titleDOM.style.color = newTitle.color
}

function renderContent (newContent, oldContent = {}) {
  if (newContent === oldContent) return // 数据没有变化就不渲染了
  console.log('render content...')
  const contentDOM = document.getElementById('content')
  contentDOM.innerHTML = newContent.text
  contentDOM.style.color = newContent.color
}

function themeReducer (state, action) {
  if (!state) return {
    themeName: 'Red Theme',
    themeColor: 'red'
  }
  switch (action.type) {
    case 'UPATE_THEME_NAME':
      return { ...state, themeName: action.themeName }
    case 'UPATE_THEME_COLOR':
      return { ...state, themeColor: action.themeColor }
    default:
      return state
  }
}

const store = createStore(themeReducer)
let oldState = store.getState() // 缓存旧的 state
store.subscribe(() => {
  const newState = store.getState() // 数据可能变化，获取新的 state
  renderApp(newState, oldState) // 把新旧的 state 传进去渲染
  oldState = newState // 渲染完以后，新的 newState 变成了旧的 oldState，等待下一次数据变化重新渲染
})

renderApp(store.getState()) // 首次渲染页面
store.dispatch({ type: 'UPDATE_TITLE_TEXT', text: '文本' }) // 修改标题文本
store.dispatch({ type: 'UPDATE_TITLE_COLOR', color: 'blue' }) // 修改标题颜色

[wuye1200]

export const connect = (mapStateToProps, mapDispatchToProps) => (WrappedComponent) => {
  class Connect extends Component {
    static contextTypes = {
      store: PropTypes.object
    }

    constructor () {
      super()
      this.state = {
        allProps: {}
      }
    }

    componentWillMount () {
      const { store } = this.context
      this._updateProps()
      store.subscribe(() => this._updateProps())
    }

    _updateProps () {
      const { store } = this.context
      let stateProps = mapStateToProps
        ? mapStateToProps(store.getState(), this.props)
        : {} // 防止 mapStateToProps 没有传入
      let dispatchProps = mapDispatchToProps
        ? mapDispatchToProps(store.dispatch, this.props)
        : {} // 防止 mapDispatchToProps 没有传入
      this.setState({
        allProps: {
          ...stateProps,
          ...dispatchProps,
          ...this.props
        }
      })
    }

    render () {
      return <WrappedComponent {...this.state.allProps} />
    }
  }
  return Connect
}

[wuye1200]

const mapStateToProps = (state) => {
  return {
    themeColor: state.themeColor
  }
}
const mapDispatchToProps = (dispatch) => {
  return {
    onSwitchColor: (color) => {
      dispatch({ type: 'CHANGE_COLOR', themeColor: color })
    }
  }
}
ThemeSwitch = connect(mapStateToProps, mapDispatchToProps)(ThemeSwitch)