← Back to TypeScript Course | Chapter 13: TypeScript with Node.js | Lesson 2 of 6

@types/node

@types/node provides TypeScript type definitions for Node.js built-in APIs. It lets TypeScript understand modules and globals such as fs, path, process, Buffer, and NodeJS types.

In this page:

  1. Installing Node.js Types
  2. Using Built-in Modules
  3. Typing process
  4. NodeJS Types
  5. Configuring Node Types
Syntax
typescript 
// npm install --save-dev @types/node
import * as fs from "fs";

const value: string | undefined = process.env.VARIABLE_NAME;

Installing Node.js Types

Installing @types/node adds type definitions for Node's built-in APIs — fs, path, process, and the rest — since Node's own runtime is plain JavaScript with no types of its own.

Example: Installing Node.js Types

typescript 
// npm install --save-dev @types/node
console.log("@types/node provides types for fs, path, process, and more");

Using Built-in Modules

With @types/node installed, importing built-in modules like fs or path gives full autocomplete and type-checked function signatures instead of TypeScript treating each import as untyped.

Example: Using Built-in Modules

typescript 
// import * as path from "path";
// const joined: string = path.join("a", "b");
console.log("With @types/node, path.join is fully typed and autocompleted");

Typing process

Typing process — its .env, .argv, and .exit() — comes from @types/node too, letting you catch a typo in an environment variable name or a wrong argument count for process.exit at compile time.

Example: Typing process

typescript 
// process.env.NODE_ENV is typed as string | undefined
// process.exit(0) requires a number argument
console.log("process.env and process.exit are typed via @types/node");

NodeJS Types

The NodeJS namespace bundled in @types/node provides types for Node-specific concepts like NodeJS.Timeout (returned by setTimeout in Node, distinct from the browser's return type) and NodeJS.ProcessEnv.

Example: NodeJS Types

typescript 
// let timeout: NodeJS.Timeout = setTimeout(() => {}, 1000);
console.log("NodeJS.Timeout differs from the browser's setTimeout return type");

Configuring Node Types

Configuring which Node types get loaded is done through the types array in tsconfig.json's compilerOptions, which matters when you want to limit ambient globals to just Node's, avoiding conflicts with browser DOM types in the same project.

Example: Configuring Node Types

typescript 
// tsconfig.json: { "compilerOptions": { "types": ["node"] } }
console.log("The types array limits ambient globals to just Node's own");
Related Topics

Setting Up TypeScript with Node · File System with Types · HTTP Module with Types · LocalStorage with Types

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Common Mistakes
  1. Forgetting @types/node, so importing fs or using process gives an error like Cannot find name process.
  2. Installing @types/node at a version that does not match your Node version, missing newer APIs.
  3. Adding it to dependencies instead of devDependencies, or expecting it to include runtime code.
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