设置为常量，书写有提示，不容易出错

    设置action类型常量 - 图1

    counter.actions.types.js

    export const INCREMENT = ‘increment’ export const DECREMENT = ‘decrement’ export const INCREMENT_N = ‘increment_n’

    Counter.actions.js

    import { INCREMENT, INCREMENT_N, DECREMENT } from‘../Action_types/counter.actions.types’ export const increment = () => ({ type:INCREMENT }) export const decrement = () => ({ type:DECREMENT }) export const increment_n = (payload) => ({ type:INCREMENT_N, payload })

    Counter.reducer.js

    import { INCREMENT, INCREMENT_N, DECREMENT } from‘../Action_types/counter.actions.types’ const initialState = { count:6 } export default (state = initialState, action) => { console.log(action) switch (action.type) { case INCREMENT: return { count:state.count + 1 } case DECREMENT: return { count:state.count - 1 } case INCREMENT_N: return { count:state.count + action.payload } default: return state } }