Bun Module Identifier

2.0.0 · active · verified Sun Apr 19

is-bun-module is a TypeScript utility library designed to programmatically identify and list modules within the Bun runtime environment. It distinguishes between Bun's native core modules (e.g., `bun:test`) and Node.js built-in modules that Bun has implemented (e.g., `fs`, `path`). The library provides functions to check individual module specifiers as well as retrieve comprehensive lists of all supported modules, optionally filtered by a specific Bun version string (e.g., '1.0.0' or 'latest'). As of version 2.0.0, the package is actively maintained with regular updates to reflect changes in Bun's module landscape, and it ships with full TypeScript type definitions for robust development.

Common errors

```
TypeError: isSupportedNodeModule is not a function
```
cause Attempting to use the old function name `isSupportedNodeModule` after upgrading to v2.0.0 or higher.

fix Rename `isSupportedNodeModule` to `isBunImplementedNodeModule`.
```
ReferenceError: require is not defined
```
cause This package is distributed as an ES Module (ESM). Using CommonJS `require()` syntax in an ESM context (e.g., a `.js` file with `"type": "module"` or a `.mjs` file) will fail.

fix Use ES module import syntax: `import { functionName } from 'is-bun-module';`.
```
TypeError: Module 'is-bun-module' has no exported member 'Version'
```
cause Attempting to import the `Version` type after upgrading to v2.0.0 or higher.

fix Update the type import from `import type { Version }` to `import type { BunVersion }`.

Warnings

breaking The function `isSupportedNodeModule` was renamed to `isBunImplementedNodeModule`.
Fix: Update all calls from `isSupportedNodeModule` to `isBunImplementedNodeModule`.
breaking The TypeScript type `Version` was renamed to `BunVersion` to avoid naming conflicts and improve clarity.
Fix: Change all type references from `Version` to `BunVersion`.
gotcha This library explicitly supports Bun v1.0.0 and newer. Using it with older Bun versions or expecting support for modules not yet implemented in v1.0.0+ may lead to unexpected results.
Fix: Ensure your Bun environment is at least v1.0.0. When querying for module support, pass the exact `bunVersion` string matching your target Bun runtime for accurate results.
gotcha The `bunVersion` parameter accepts semantic version strings (e.g., '1.0.0', '1.0.13') or the literal string 'latest'. Providing an invalid format will result in unpredictable behavior.
Fix: Always pass a valid semantic version string or 'latest' to the `bunVersion` parameter.

Install

npm install is-bun-module npm
yarn add is-bun-module yarn
pnpm add is-bun-module pnpm

Imports

isBunModule
wrong:
```
const isBunModule = require('is-bun-module').isBunModule;
```
correct:
```
import { isBunModule } from 'is-bun-module';
```
Primary function for checking Bun-specific modules. This package is primarily ESM.
isBunImplementedNodeModule
wrong:
```
import { isSupportedNodeModule } from 'is-bun-module';
```
correct:
```
import { isBunImplementedNodeModule } from 'is-bun-module';
```
Checks for Node.js modules implemented by Bun. Renamed from `isSupportedNodeModule` in v2.0.0.

getBunBuiltinModules

wrong:

const getBunBuiltinModules = require('is-bun-module').getBunBuiltinModules;

correct:

import { getBunBuiltinModules } from 'is-bun-module';

Retrieves a combined list of all Bun and Bun-implemented Node.js modules.

BunVersion
wrong:
```
import type { Version } from 'is-bun-module';
```
correct:
```
import type { BunVersion } from 'is-bun-module';
```
Type definition for Bun version specifiers. Renamed from `Version` to `BunVersion` in v2.0.0.

Quickstart

Demonstrates how to use `isBunModule`, `isBunImplementedNodeModule`, and `getBunBuiltinModules` to identify and list modules, including specifying Bun versions.

import { 
  isBunModule,
  isBunImplementedNodeModule,
  getBunBuiltinModules,
  BunVersion 
} from 'is-bun-module';

// Check specific Bun modules
console.log('Is "bun" a Bun module?', isBunModule('bun'));
console.log('Is "bun:test" a Bun module (Bun v1.0.0)?', isBunModule('bun:test', '1.0.0' as BunVersion));
console.log('Is "notBunModule" a Bun module?', isBunModule('notBunModule'));

// Check Node.js modules implemented in Bun
console.log('Is "fs" a Bun-implemented Node module?', isBunImplementedNodeModule('fs'));
console.log('Is "node:http2" a Bun-implemented Node module (Bun v1.0.0)?', isBunImplementedNodeModule('node:http2', '1.0.0' as BunVersion));

// Get a list of all builtin modules for the latest Bun version
const latestBuiltins = getBunBuiltinModules('latest');
console.log('First 5 builtin modules (latest Bun):', latestBuiltins.slice(0, 5));

// Example with an older Bun version
const bunV1_0_0Builtins = getBunBuiltinModules('1.0.0' as BunVersion);
console.log('Number of builtin modules in Bun v1.0.0:', bunV1_0_0Builtins.length);

// Type assertion for clarity when passing string literals as BunVersion
const currentBunVersion: BunVersion = '1.0.13';
console.log(`Checking 'crypto' against Bun ${currentBunVersion}:`, isBunImplementedNodeModule('crypto', currentBunVersion));

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