如果不清楚 可以查看https://segmentfault.com/a/1190000018395291
bindActionCreators就是給action創(chuàng)建函數(shù)綁定了dispatch,可以直接以普通函數(shù)執(zhí)行,而不用dispatch(actionCreator)這樣寫.比如下面,bindActionCreators生成一個(gè)對(duì)象,對(duì)象里面的value值是function,那么可以直接this.boundActionCreators.addTodo()執(zhí)行**
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源碼:
function bindActionCreator(actionCreator, dispatch) {
? ? ? return (...args) => dispatch(actionCreator(...args))
}
/**
* Turns an object whose values are action creators, into an object with the
* same keys, but with every function wrapped into a `dispatch` call so they
* may be invoked directly. This is just a convenience method, as you can call
* `store.dispatch(MyActionCreators.doSomething())` yourself just fine.
*
* 將一個(gè)value值是action創(chuàng)建函數(shù)的對(duì)象變成一個(gè)具有相同key值的對(duì)象,但是每個(gè)函數(shù)都被封裝到
* `dispatch`回調(diào)里面,這樣它們就有可能被直接觸發(fā). 這樣只是比較方便,你也可以調(diào)用
* `store.dispatch(MyActionCreators.doSomething())`
*
* For convenience, you can also pass a single function as the first argument,
* and get a function in return.
*
* 為了方便,你也可以傳單個(gè)函數(shù)作為第一個(gè)參數(shù),然后返回一個(gè)函樹
*
* @param {Function|Object} actionCreators An object whose values are action
* creator functions. One handy way to obtain it is to use ES6 `import * as`
* syntax. You may also pass a single function.
*
* actionCreators 是一個(gè)value值是action創(chuàng)建函數(shù)的對(duì)象,一個(gè)很方便獲取到它的方法就是
* 使用ES6 的`import * as `語(yǔ)法.也可以傳單個(gè)函數(shù)
*
* @param {Function} dispatch The `dispatch` function available on your Redux
* store.
*
* dispatch就是redux 里store的dispatch
*
* @returns {Function|Object} The object mimicking the original object, but with
* every action creator wrapped into the `dispatch` call. If you passed a
* function as `actionCreators`, the return value will also be a single
* function.
*
* 返回的對(duì)象和初始的對(duì)選象很像,但每一個(gè)action創(chuàng)建函數(shù)都給封裝到`dispatch`回調(diào)里面
* 如果你傳單個(gè)函數(shù)作為`actionCreators`,那返回值也是一個(gè)單個(gè)函數(shù)
*/
export default function bindActionCreators(actionCreators, dispatch) {
? ? ? ? ? ? ? if (typeof actionCreators === 'function') {
? ? ? ? ? ? ? ? ? ? ? ? ? ?return bindActionCreator(actionCreators, dispatch)
? ? ? ? ? ? ? ?}
? ? ? ? ? ? ? if (typeof actionCreators !== 'object' || actionCreators === null) {
? ? ? ? ? ? ? ? ? ?throw new Error(
? ? ? ? ? ? ? ? ? ? ? ? `bindActionCreators expected an object or a function, instead received ${actionCreators === null ? 'null' : typeof? ? ? ? ? ? ? ? ? ? ? ? ? actionCreators}. ` +`Did you write "import ActionCreators from" instead of "import * as ActionCreators from"?`
? ? ? ? ? ? ? ? ? )
? ? ? ? ? ? ? ? ? ? ?//bindActionCreators的參數(shù)應(yīng)該是對(duì)象或者函數(shù),而不是空或其他類型,
? ? ? ? ? ? ? ? ? ? ?//你是不是把"import * as ActionCreators from"寫成了"import ActionCreators from"?
? ? ? ? ? ? ? ? }
const keys = Object.keys(actionCreators)
? ? ? ? ? ? ? ?const boundActionCreators = {}
? ? ? ? ? ? ? ?for (let i = 0; i < keys.length; i++) {
? ? ? ? ? ? ? ? ? ? ? const key = keys[i]
? ? ? ? ? ? ? ? ? ? ? const actionCreator = actionCreators[key]
? ? ? ? ? ? ? ? ? ? ? if (typeof actionCreator === 'function') {
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? boundActionCreators[key] = bindActionCreator(actionCreator, dispatch)
? ? ? ? ? ? ? ? ? ? ? ?}
? ? ? ? ? ? ? ?}
? ? ? ? ? ? return boundActionCreators
}
