Modules: module API | Node.js v15.14.0 Documentation (original) (raw)

Added in: v0.3.7

The Module object#

Provides general utility methods when interacting with instances ofModule, the module variable often seen in CommonJS modules. Accessed via import 'module' or require('module').

module.builtinModules#

Added in: v9.3.0, v8.10.0, v6.13.0

• <string[]>

A list of the names of all modules provided by Node.js. Can be used to verify if a module is maintained by a third party or not.

module in this context isn't the same object that's provided by the module wrapper. To access it, require the Module module:

// module.mjs // In an ECMAScript module import { builtinModules as builtin } from 'module'; // module.cjs // In a CommonJS module const builtin = require('module').builtinModules;

module.createRequire(filename)#

Added in: v12.2.0

• filename | Filename to be used to construct the require function. Must be a file URL object, file URL string, or absolute path string.
• Returns: Require function

import { createRequire } from 'module';
const require = createRequire(import.meta.url);

// sibling-module.js is a CommonJS module.
const siblingModule = require('./sibling-module');

module.createRequireFromPath(filename)#

Added in: v10.12.0Deprecated since: v12.2.0

• filename Filename to be used to construct the relative require function.
• Returns: Require function

const { createRequireFromPath } = require('module');
const requireUtil = createRequireFromPath('../src/utils/');

// Require `../src/utils/some-tool`
requireUtil('./some-tool');

module.syncBuiltinESMExports()#

Added in: v12.12.0

The module.syncBuiltinESMExports() method updates all the live bindings for builtin ES Modules to match the properties of the CommonJS exports. It does not add or remove exported names from the ES Modules.

const fs = require('fs');
const assert = require('assert');
const { syncBuiltinESMExports } = require('module');

fs.readFile = newAPI;

delete fs.readFileSync;

function newAPI() {
  // ...
}

fs.newAPI = newAPI;

syncBuiltinESMExports();

import('fs').then((esmFS) => {
  // It syncs the existing readFile property with the new value
  assert.strictEqual(esmFS.readFile, newAPI);
  // readFileSync has been deleted from the required fs
  assert.strictEqual('readFileSync' in fs, false);
  // syncBuiltinESMExports() does not remove readFileSync from esmFS
  assert.strictEqual('readFileSync' in esmFS, true);
  // syncBuiltinESMExports() does not add names
  assert.strictEqual(esmFS.newAPI, undefined);
});

Source map v3 support#

Added in: v13.7.0, v12.17.0

Helpers for interacting with the source map cache. This cache is populated when source map parsing is enabled andsource map include directives are found in a modules' footer.

To enable source map parsing, Node.js must be run with the flag--enable-source-maps, or with code coverage enabled by settingNODE_V8_COVERAGE=dir.

// module.mjs // In an ECMAScript module import { findSourceMap, SourceMap } from 'module'; // module.cjs // In a CommonJS module const { findSourceMap, SourceMap } = require('module');

module.findSourceMap(path)#

Added in: v13.7.0, v12.17.0

• path
• Returns: <module.SourceMap>

path is the resolved path for the file for which a corresponding source map should be fetched.

Class: module.SourceMap#

Added in: v13.7.0, v12.17.0

new SourceMap(payload)#

• payload

Creates a new sourceMap instance.

payload is an object with keys matching the Source map v3 format:

• file:
• version:
• sources: <string[]>
• sourcesContent: <string[]>
• names: <string[]>
• mappings:
• sourceRoot:

sourceMap.payload#

• Returns:

Getter for the payload used to construct the SourceMap instance.

sourceMap.findEntry(lineNumber, columnNumber)#

• lineNumber
• columnNumber
• Returns:

Given a line number and column number in the generated source file, returns an object representing the position in the original file. The object returned consists of the following keys:

• generatedLine:
• generatedColumn:
• originalSource:
• originalLine:
• originalColumn:
• name: