Node.js Type Definitions

Install @types/node as a development dependency for Node.js API type declarations. It provides compiler knowledge of process, Buffer, and node: imports; it does not install or run Node itself. Select compatible type definitions for the Node version targeted by the application and do not accidentally depend on Node globals in browser-only bundles.

The Buffer class is a runtime Node value. @types/node supplies the Buffer type and method signatures for the compiler, while Node performs the UTF-8 encoding and hexadecimal formatting.

Type declaration packages do not polyfill missing runtime APIs or make Node imports work inside a web page.

Save as node-js-type-definitions.ts. The following program passed strict TypeScript compilation, and the displayed output was captured by executing its emitted JavaScript with Node.js 22.16.0.

TypeScript source

import { Buffer } from "node:buffer";
const bytes: Buffer = Buffer.from("TS", "utf8");
console.log(bytes.toString("hex"));
console.log(bytes.length);

Verified output

5453
2

Compile: npx tsc --strict --target es2022 --module commonjs node-js-type-definitions.ts; run: node node-js-type-definitions.js. For Node.js API examples, install @types/node first. For browser projects, use the browser-specific instructions below.

The example runs in Node.js 22.16.0; if it reads runtime environment details, your displayed values may differ.

The Buffer class is a runtime Node value. @types/node supplies the Buffer type and method signatures for the compiler, while Node performs the UTF-8 encoding and hexadecimal formatting.

Predict what changes if you alter one input. Then run the code to compare your reasoning with the real output.

Type declaration packages do not polyfill missing runtime APIs or make Node imports work inside a web page.

Identify whether the failure is a type-checking issue, a configuration issue, or a runtime behavior issue before choosing a fix.

Install typescript and @types/node in a new project and type-check a Buffer example with npx tsc --noEmit.

Write down your expected result first. For configuration examples, compare compiler output and diagnostics; for test examples, make the assertion fail deliberately to verify that the tool reports it.

Install @types/node as a development dependency for Node.

Run the primary example, then complete the practice task or environment-specific lab.