redux的bindActionCreators源碼,中文翻譯

MockingBird 發(fā)布于2019-08-23 15:39 / 2363人閱讀

摘要：就是給創(chuàng)建函數(shù)綁定了可以直接以普通函數(shù)執(zhí)行而不用這樣寫比如下面生成一個對象對象里面的值是那么可以直接執(zhí)行將一個值是創(chuàng)建函數(shù)的對象變成一個具有相同值的對象但是每個函數(shù)都被封裝到回調(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)用為了

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生成一個對象,對象里面的value值是function,
那么可以直接this.boundActionCreators.addTodo()執(zhí)行**

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value值是action創(chuàng)建函數(shù)的對象變成一個具有相同key值的對象,但是每個函數(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,你也可以傳單個函數(shù)作為第一個參數(shù),然后返回一個函樹
 * 
 * @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value值是action創(chuàng)建函數(shù)的對象,一個很方便獲取到它的方法就是
 * 使用ES6 的`import * as `語法.也可以傳單個函數(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.
 * 
 * 返回的對象和初始的對選象很像,但每一個action創(chuàng)建函數(shù)都給封裝到`dispatch`回調(diào)里面
 * 如果你傳單個函數(shù)作為`actionCreators`,那返回值也是一個單個函數(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) //就是(...args) => dispatch(actionCreator(...args))
    }
  }
  return boundActionCreators
}

源碼解析請參考https://segmentfault.com/a/11...