⚛️ React Errors

32 error notes

Warning: React has detected a change in the order of Hooks called by ComponentName. This will lead to bugs and errors if not fixed. For more information, read the Rules of Hooks: https://reactjs.org/link/rules-of-hooks

reacthooksrules-of-hooksdebugging

reactintermediate

styled-componentsのReact SSRで'Prop className did not match'警告を修正する

Warning: Prop `className` did not match. Server: "sc-bdVTJa" Client: "sc-fzoLsD"

reactstyled-componentsssrhydration

reactbeginner

Reactでの「Element type is invalid: expected a string but got: undefined」エラーの修正方法

React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

reactjavascriptデバッグフロントエンド

reactintermediate

ChunkLoadError: Loading chunk failedをReactプロダクションビルドで修正する方法

ChunkLoadError: Loading chunk 3 failed. (error: https://example.com/static/js/3.chunk.js)

webpackコード分割react-lazyプロダクション

reactintermediate

Reactの「Cannot update a component while rendering a different component」を修正する

Warning: Cannot update a component (`App`) while rendering a different component (`Child`). To locate the bad setState() call inside `Child`, follow the stack trace as described in https://reactjs.org/link/setstate-in-render

reactsetStateレンダリング副作用

reactintermediate

「React Hook useEffectに依存関係が不足しています」警告がサイレントバグを引き起こす問題を修正する

React Hook useEffect has a missing dependency: 'someVariable'. Either include it or remove the dependency array.  react-hooks/exhaustive-deps

reactuseEffecteslinthooks

reactbeginner

ReactでDOM要素にbooleanプロップを渡す際の「Received true for a non-boolean attribute」警告を修正する

Warning: Received `true` for a non-boolean attribute `loading`. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `loading` instead. If you accidentally passed it from a parent component, remove it from the DOM element.

dompropsboolean-attributehtml

reactbeginner

Reactで「Rendered more hooks than during the previous render」を修正する

Error: Rendered more hooks than during the previous render.

reacthooksrules-of-hooksconditional-rendering

reactintermediate

React.forwardRefで「Function components cannot be given refs」を修正する

Warning: Function components cannot be given refs. Attempts to access this ref will fail. Did you mean to use React.forwardRef()?

reactforwardRefrefhooks

reactbeginner

「Objects are not valid as a React child (found: object with keys {then})」の修正 — JSXでPromiseをレンダリングしている場合

Objects are not valid as a React child (found: object with keys {then}). If you meant to render a collection of children, use an array instead.

reactpromiseasyncjsx

reactbeginner

Reactの「制御されていない入力が制御されるように変更されています」を修正する

Warning: A component is changing an uncontrolled input of type 'text' to be controlled. Input elements should not switch from uncontrolled to controlled (or vice versa).

reactフォーム制御コンポーネントstate

reactintermediate

Next.jsで「useSearchParams() should be wrapped in a suspense boundary」エラーを修正する方法

Error: useSearchParams() should be wrapped in a suspense boundary at page "/search". Read more: https://nextjs.org/docs/messages/missing-suspense-with-csr-bailout

reactnextjssuspenseusesearchparams

reactbeginner

解決済み：React 18 で ReactDOM.render が非推奨に

Warning: ReactDOM.render is no longer supported in React 18. Use createRoot instead. Until you switch to the new API, your app will behave as if it's running React 17.

reactreact18web-devjavascript

react初級者

ReactのvalidateDOMNestingエラーの修正：<p>の中に<div>を入れないでください

Warning: validateDOMNesting(...): <div> cannot appear as a descendant of <p>. See ... > p > div.

reactdomhtmlネスト

reactintermediate

「React does not recognize prop on a DOM element」警告の解決方法

Warning: React does not recognize the `isActive` prop on a DOM element. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `isactive` instead.

reactWeb開発styled-componentsフロントエンド

reactintermediate

ReactアプリでCORSポリシーによるブロックエラーを修正する方法

Access to fetch at 'http://api.example.com' from origin 'http://localhost:3000' has been blocked by CORS policy

reactcorsapifetch

reactintermediate

ReactのSSR/Next.jsで「useLayoutEffect does nothing on the server」警告を修正する

Warning: useLayoutEffect does nothing on the server because its effect cannot be encoded into the server renderer's output format. This will lead to a mismatch between the initial, non-hydrated UI and the intended UI.

reactnextjsssruseLayoutEffect

reactintermediate

ReactテストでWarning: An update to inside a test was not wrapped in act(...)を修正する

Warning: An update to ForwardRef inside a test was not wrapped in act(...). When testing, code that causes React state updates should be wrapped into act(...).

reacttestingactreact-testing-library

reactbeginner