React Typescript "Cannot find name" error [Solved]

# React Typescript "Cannot find name" error [Solved]

To solve the "Cannot find name" error in React typescript, use a .tsx extension for the files in which you use JSX, set jsx to react-jsx in your tsconfig.json file and make sure to install all of the necessary @types packages for your application.

typescript react cannot find name

Here is an example of how the error occurs in a file called App.ts.

App.ts

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export default function App() {
  // ⛔️ Cannot find name 'div'.ts(2304)
  return (
    <div>
      <input type="text" id="message" defaultValue="Initial value" />
      {/* Cannot find name 'button'.ts(2304) */}
      <button>Click</button>
    </div>
  );
}

The issue in the code sample is that our file has a .ts extension and we're writing JSX code in it.

This is not allowed because to use JSX in a TypeScript file, we have to:

Name our files with a .tsx extension
Enable the jsx option in our tsconfig.json file

# All files in which you write JSX code must have a `.tsx` extension

Make sure all of the files in which you write JSX code have a .tsx extension.

App.tsx

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export default function App() {
  return (
    <div>
      <input
        type="text"
        id="message"
        defaultValue="Initial value"
      />
      <button>Click</button>
    </div>
  );
}

all files in which you write jsx code must have tsx extension

The code for this article is available on GitHub

If the error is not resolved after updating the file's extension to .tsx, try restarting your IDE and development server.

# Make sure the `jsx` property is set to `react-jsx`

Open your tsconfig.json file and make sure the jsx option is set to react-jsx.

tsconfig.json

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{
  "compilerOptions": {
    "jsx": "react-jsx", // 👈️ make sure you have this
    "target": "es6",
    "lib": ["dom", "dom.iterable", "esnext"],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "noFallthroughCasesInSwitch": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true
  },
  "include": ["src/**/*"]
}

When the jsx option is set to react-jsx, it causes the compiler to emit .js files with the JSX changed to _jsx calls.

Make sure to restart your development server and your IDE if necessary. Your dev server won't pick up the changes until you stop it and re-run the npm start command.

# Make sure you have the `@types/` packages installed

Another cause of the error in React TypeScript is when we don't install the necessary @types/ packages.

Open your terminal in the root directory of your project (where your package.json file is) and run the following command:

shell

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# 👇️ with NPM
npm install --save-dev @types/react @types/react-dom @types/node @types/jest typescript

# ------------------------------------------------------

# 👇️ with YARN
yarn add @types/react @types/react-dom @types/node @types/jest typescript --dev

make sure types packages are installed

The command installs the typings for react, react-dom, node, jest and also installs the typescript package.

The code for this article is available on GitHub

# Delete your node_modules and reinstall your dependencies

If you still get the error, try to delete your node_modules and package-lock.json (not package.json) files, re-run npm install and restart your IDE.

If you are on macOS or Linux, issue the following commands in bash or zsh.

shell

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#  for macOS and Linux
rm -rf node_modules
rm -f package-lock.json
rm -f yarn.lock

# 👇️ clean npm cache
npm cache clean --force

# 👇️ install packages
npm install

If you are on Windows, issue the following commands in CMD.

cmd

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# for Windows
rd /s /q "node_modules"
del package-lock.json
del -f yarn.lock

# 👇️ clean npm cache
npm cache clean --force

# 👇️ install packages
npm install

Make sure to restart your IDE and dev server if the error persists. VSCode often glitches and a reboot solves things sometimes.

# Make sure the necessary modules are installed

If you still get the error, open your package.json file and make sure it contains the following packages in the devDependencies object.

package.json

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{
  // ... rest
  "devDependencies": {
    "@types/react": "^17.0.44",
    "@types/react-dom": "^17.0.15",
    "@types/jest": "^27.4.1",
    "@types/node": "^17.0.23",
    "typescript": "^4.6.3"
  }
}

You can try to manually add the lines and re-run npm install.

shell

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npm install

Or install the latest version of the packages:

shell

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# 👇️ with NPM
npm install --save-dev @types/react@latest @types/react-dom@latest @types/node@latest @types/jest@latest typescript@latest

# ------------------------------------------------------

# 👇️ with YARN
yarn add @types/react@latest @types/react-dom@latest @types/node@latest @types/jest@latest typescript@latest --dev

install latest version of typings