Configuring module and moduleResolution

module controls emitted module syntax; moduleResolution controls how imports are interpreted during type checking. NodeNext models modern Node package rules, while Bundler fits bundler-managed dependencies. Align both options with the actual runtime/build pipeline; changing a compiler flag does not install a module loader.

The exported function can be emitted in CommonJS or ES Module form depending on module. Its calculation stays the same; a separate import must resolve and load with matching runtime rules.

Setting moduleResolution:"bundler" does not turn Node.js into a bundler or fix unsupported runtime import specifiers.

Save as configuring-module-moduleresolution.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

export function double(value: number): number { return value * 2; }
console.log(double(6));

Verified output

12

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

The example demonstrates the code-level behavior; the related configuration or test commands are shown separately when needed.

The exported function can be emitted in CommonJS or ES Module form depending on module. Its calculation stays the same; a separate import must resolve and load with matching runtime rules.

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

Practical project lab: These are real configuration and source-file examples, not a TypeScript object that merely describes settings. Place the files at the named paths relative to one project directory.

package.json

{"type":"module"}

tsconfig.json

{"compilerOptions":{"target":"ES2022","module":"NodeNext","moduleResolution":"NodeNext","strict":true}}

main.ts

import { square } from "./square.js";
console.log(square(5));

square.ts

export const square = (n: number): number => n * n;

Commands

npx tsc -p .
node main.js

NodeNext ESM uses emitted .js import specifiers in .ts source.

This local compiler or test-runner mini-project was validated in addition to the primary program.

Setting moduleResolution:"bundler" does not turn Node.js into a bundler or fix unsupported runtime import specifiers.

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

Create two files, import one from the other, and compare a CommonJS build with NodeNext ESM.

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.

For the exact current options and platform behavior, consult the official documentation. These examples were verified using the tool versions described above.

module controls emitted module syntax; moduleResolution controls how imports are interpreted during type checking.

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