How to fix Cannot find name 'require' in TypeScript

The most common fix is to install the Node.js type definitions package:

Install @types/node as a dev dependency:

npm install --save-dev @types/node

Or with Yarn:

yarn add --dev @types/node

Or with pnpm:

pnpm add --save-dev @types/node

Verify the installation:

npm list @types/node

After installation, the TypeScript compiler will have access to the type definitions for require() and other Node.js globals. Your IDE should immediately recognize require() and the red squiggles should disappear.

Note: @types/node is a "dev" dependency because it's only needed during development/compilation. The types are not included in your production bundle.

Even after installing @types/node, you may need to explicitly add it to your TypeScript configuration:

Edit tsconfig.json:

{
  "compilerOptions": {
    "target": "es2020",
    "module": "commonjs",
    "lib": ["es2020"],
    "types": ["node"],
    // ... other options
  }
}

The "types" array tells TypeScript which type definitions to include. By default (when not specified), TypeScript includes all installed @types packages. However, if you have explicitly set a "types" array with other values, you must include "node" to get Node.js types.

Example of restrictive types that breaks require():

{
  "compilerOptions": {
    "types": ["jest"]  // This restricts types to ONLY jest, excluding node!
  }
}

Solution - add node:

{
  "compilerOptions": {
    "types": ["node", "jest"]  // Now both node and jest types are available
  }
}

After updating tsconfig.json, restart your IDE or TypeScript language server for changes to take effect.

Ensure your tsconfig.json is configured for Node.js environments:

For CommonJS projects (using require):

{
  "compilerOptions": {
    "target": "es2020",
    "module": "commonjs",
    "lib": ["es2020"],
    "moduleResolution": "node",
    "types": ["node"]
  }
}

For ES Modules projects (using import):

{
  "compilerOptions": {
    "target": "es2020",
    "module": "esnext",
    "lib": ["es2020"],
    "moduleResolution": "node",
    "types": ["node"]
  }
}

Key options explained:
- module: "commonjs" for require(), "esnext" for import/export
- moduleResolution: "node" to use Node.js module resolution algorithm
- lib: Defines the built-in types available (es2020 is modern)
- types: Includes Node.js type definitions

The lib option affects built-in globals. If you omit "lib" entirely, TypeScript defaults to the DOM, which doesn't include Node.js globals.

If your project supports it, consider migrating from require() to ES6 import syntax:

Convert require to import:

Old CommonJS style:

const express = require('express');
const fs = require('fs');

const app = express();
const data = fs.readFileSync('./file.txt', 'utf-8');

New ES6 style:

import express from 'express';
import fs from 'fs';

const app = express();
const data = fs.readFileSync('./file.txt', 'utf-8');

Update tsconfig.json for ES modules:

{
  "compilerOptions": {
    "target": "es2020",
    "module": "esnext",
    "moduleResolution": "node",
    "types": ["node"]
  }
}

Update package.json (if not already):

{
  "type": "module"
}

ES6 imports are the modern standard and work in Node.js 12+. They're also what browsers natively support, making your code more compatible with different environments.

Sometimes the error persists even after fixes due to caching:

For VS Code:
1. Press Ctrl+Shift+P (or Cmd+Shift+P on Mac)
2. Type "TypeScript: Restart TS Server"
3. Press Enter

Or reload the window:
1. Press Ctrl+Shift+P
2. Type "Developer: Reload Window"
3. Press Enter

For other editors:
- Restart your IDE completely
- Delete node_modules and reinstall:

rm -rf node_modules package-lock.json
npm install

Clear TypeScript cache:

# Remove TypeScript build cache
rm -rf .tsbuildinfo

# For monorepos, might be in different locations
find . -name "*.tsbuildinfo" -delete

After restarting, TypeScript should recognize the types from @types/node and the error should disappear.

After fixing the compile-time error, ensure require() actually works when your code runs:

Check your execution context:

// This works in Node.js
const path = require('path');

// But NOT in browsers or bundlers without special setup
// Browsers don't have require() at all

For browser environments:
If you're building for browsers, you cannot use require() at all. You must use ES6 imports and a bundler like Webpack or Rollup:

// ❌ Won't work in browsers
const _ = require('lodash');

// ✅ Works in browsers with proper bundler
import _ from 'lodash';

For Node.js with ES Modules:
If using "type": "module" in package.json, you must use import/export, not require():

// ❌ Error: require is not defined
const express = require('express');

// ✅ Correct for ES Modules
import express from 'express';

For monorepos or build systems:
Ensure your build tool (esbuild, swc, vite, etc.) is configured to handle the module format you're using.