章节 8 - dispatch-async-action-2.js
运行之前我们在 dispatch-async-action-1.js 中实现的第一个异步 action creator:
import { createStore, combineReducers } from 'redux'
var reducer = combineReducers({
speaker: function (state = {}, action) {
console.log('speaker was called with state', state, 'and action', action)
switch (action.type) {
case 'SAY':
return {
...state,
message: action.message
}
default:
return state;
}
}
})
var store_0 = createStore(reducer)
var asyncSayActionCreator_1 = function (message) {
return function (dispatch) {
setTimeout(function () {
dispatch({
type: 'SAY',
message
})
}, 2000)
}
}
console.log("\n", 'Running our async action creator:', "\n")
store_0.dispatch(asyncSayActionCreator_1('Hi'))
// 输出:
// ...
// /Users/classtar/Codes/redux-tutorial/node_modules/redux/node_modules/invariant/invariant.js:51
// throw error;
// ^
// Error: Invariant Violation: Actions must be plain objects. Use custom middleware for async actions.
// ...
我们所设计的 function 似乎没有进入 reducer 函数。但是 Redux 给出了温馨提示:使用自定义中间件(middleware)来支持异步 action。看来我们的方向是正确的,可中间件(middleware)又是什么呢?
我向你保证 action creator asyncSayActionCreator_1 不仅没有问题,而且只要我们搞清楚 middleware 的概念并掌握它的使用方法,这个异步 action creator 就会按照我们所设想的结果执行。
开始下节教程:09_middleware.js