3

我在浏览器的本地主机端口上收到一条错误消息，我还没有部署我的代码：

TypeError: Object(...) 不是函数

NewEvent src/events/pages/NewEvent.js:51

这是我在 package.json 中的反应版本：

  "dependencies": {
    "react": "^16.13.1",
    "react-dom": "^16.13.1",
    "react-router-dom": "5.2.0",
    "react-scripts": "^3.2.0",
    "react-transition-group": "^4.4.1"
  },

我在我的页面中导入了 NewEvent.js ：

import React, {useCallBack , useReducer} from 'react';

在同一页面中，我在一个函数中嵌套了另一个函数：

  const [formState, dispatch] = useReducer(formReducer, {
    inputs: {
      title: {
        value: '',
        isValid: false
      },
      description: {
        value: '',
        isValid: false
      }
    },
    isValid: false
  });// this is the initial state that needs  to be update in the reducer

  const inputHandler = useCallBack((id,value,isValid) => {
 
  dispatch({
    type: 'INPUT_CHANGE',
    value: value,
    isValid: isValid,
    inputId: id,
   });
 }, []);

浏览器中显示的问题是以下行：

  const inputHandler = useCallBack((id,value,isValid) => {

当有多个函数时，useCallBack 应该停止代码循环。我在其他帖子中在线查看它似乎与反应版本有关，但我不确定并且很困惑。

这里是控制台中的消息：

log.js:24 [HMR] Waiting for update signal from WDS...
NewEvent.js:51 Uncaught TypeError: Object(...) is not a function

    at NewEvent (NewEvent.js:51)
    at renderWithHooks (react-dom.development.js:14803)
    at mountIndeterminateComponent (react-dom.development.js:17482)
    at beginWork (react-dom.development.js:18596)
    at HTMLUnknownElement.callCallback (react-dom.development.js:188)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:237)
    at invokeGuardedCallback (react-dom.development.js:292)
    at beginWork$1 (react-dom.development.js:23203)
    at performUnitOfWork (react-dom.development.js:22154)
    at workLoopSync (react-dom.development.js:22130)
    at performSyncWorkOnRoot (react-dom.development.js:21756)
    at scheduleUpdateOnFiber (react-dom.development.js:21188)
    at updateContainer (react-dom.development.js:24373)
    at react-dom.development.js:24758
    at unbatchedUpdates (react-dom.development.js:21903)
    at legacyRenderSubtreeIntoContainer (react-dom.development.js:24757)
    at Object.render (react-dom.development.js:24840)
    at Module../src/index.js (index.js:7)
    at __webpack_require__ (bootstrap:784)
    at fn (bootstrap:150)
    at Object.1 (Users.js:19)
    at __webpack_require__ (bootstrap:784)
    at checkDeferredModules (bootstrap:45)
    at Array.webpackJsonpCallback [as push] (bootstrap:32)
    at main.chunk.js:1
index.js:1 The above error occurred in the <NewEvent> component:
    in NewEvent (at App.js:23)
    in Route (at App.js:22)
    in Switch (at App.js:15)
    in main (at App.js:14)
    in Router (created by BrowserRouter)
    in BrowserRouter (at App.js:11)
    in App (at src/index.js:7)

Consider adding an error boundary to your tree to customize error handling behavior.
react-dom.development.js:22665 Uncaught TypeError: Object(...) is not a function
    at NewEvent (NewEvent.js:51)
    at renderWithHooks (react-dom.development.js:14803)
    at mountIndeterminateComponent (react-dom.development.js:17482)
    at beginWork (react-dom.development.js:18596)
    at HTMLUnknownElement.callCallback (react-dom.development.js:188)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:237)
    at invokeGuardedCallback (react-dom.development.js:292)
    at beginWork$1 (react-dom.development.js:23203)
    at performUnitOfWork (react-dom.development.js:22154)
    at workLoopSync (react-dom.development.js:22130)
    at performSyncWorkOnRoot (react-dom.development.js:21756)
    at scheduleUpdateOnFiber (react-dom.development.js:21188)
    at updateContainer (react-dom.development.js:24373)
    at react-dom.development.js:24758
    at unbatchedUpdates (react-dom.development.js:21903)
    at legacyRenderSubtreeIntoContainer (react-dom.development.js:24757)
    at Object.render (react-dom.development.js:24840)
    at Module../src/index.js (index.js:7)
    at __webpack_require__ (bootstrap:784)
    at fn (bootstrap:150)
    at Object.1 (Users.js:19)
    at __webpack_require__ (bootstrap:784)
    at checkDeferredModules (bootstrap:45)
    at Array.webpackJsonpCallback [as push] (bootstrap:32)
    at main.chunk.js:1

浏览器上显示的消息：

NewEvent
src/events/pages/NewEvent.js:51
  48 |   isValid: false
  49 | });// this is the initial state that needs  to be update in the reducer
  50 | 
> 51 | const inputHandler = useCallBack((id,value,isValid) => {
     | ^  52 | //this function will received the id of the input that changed, value and answer whether it's valid or not
  53 | dispatch({
  54 |   type: 'INPUT_CHANGE',

View compiled
16 stack frames were collapsed.
Module../src/index.js

请问有人知道这个问题吗？

-- 抱歉我的帖子很长 -- :D

4

1 回答 1

7

所以我花了一些时间试图重新创建这个错误，最终意识到这是一个不幸的错字案例。

简而言之，这样做：（import React, { useCallback, useReducer } from "react";注意回调中的小写b）。

仅考虑这么多信息，很难收集实际错误是什么：TypeError: undefined is not a function.

但是，关于 TypeError 的 MDN文档（除其他外）指出：

也许函数名称中有错字？

希望这可以帮助！

于 2020-07-01T00:31:59.190 回答