Current File : //usr/share/doc/nodejs/api/module.md
# Modules: `module` API
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## The `Module` object
* {Object}
Provides general utility methods when interacting with instances of
`Module`, the [`module`][] variable often seen in [CommonJS][] modules. Accessed
via `import 'module'` or `require('module')`.
### `module.builtinModules`
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* {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:
```mjs
// module.mjs
// In an ECMAScript module
import { builtinModules as builtin } from 'module';
```
```cjs
// module.cjs
// In a CommonJS module
const builtin = require('module').builtinModules;
```
### `module.createRequire(filename)`
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* `filename` {string|URL} Filename to be used to construct the require
function. Must be a file URL object, file URL string, or absolute path
string.
* Returns: {require} Require function
```mjs
import { createRequire } from 'module';
const require = createRequire(import.meta.url);
// sibling-module.js is a CommonJS module.
const siblingModule = require('./sibling-module');
```
### `module.syncBuiltinESMExports()`
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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][].
```js
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
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> Stability: 1 - Experimental
Helpers for interacting with the source map cache. This cache is
populated when source map parsing is enabled and
[source 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 setting
[`NODE_V8_COVERAGE=dir`][].
```mjs
// module.mjs
// In an ECMAScript module
import { findSourceMap, SourceMap } from 'module';
```
```cjs
// module.cjs
// In a CommonJS module
const { findSourceMap, SourceMap } = require('module');
```
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### `module.findSourceMap(path)`
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* `path` {string}
* Returns: {module.SourceMap}
`path` is the resolved path for the file for which a corresponding source map
should be fetched.
### Class: `module.SourceMap`
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#### `new SourceMap(payload)`
* `payload` {Object}
Creates a new `sourceMap` instance.
`payload` is an object with keys matching the [Source map v3 format][]:
* `file`: {string}
* `version`: {number}
* `sources`: {string\[]}
* `sourcesContent`: {string\[]}
* `names`: {string\[]}
* `mappings`: {string}
* `sourceRoot`: {string}
#### `sourceMap.payload`
* Returns: {Object}
Getter for the payload used to construct the [`SourceMap`][] instance.
#### `sourceMap.findEntry(lineNumber, columnNumber)`
* `lineNumber` {number}
* `columnNumber` {number}
* Returns: {Object}
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: {number}
* generatedColumn: {number}
* originalSource: {string}
* originalLine: {number}
* originalColumn: {number}
* name: {string}
[CommonJS]: modules.md
[ES Modules]: esm.md
[Source map v3 format]: https://sourcemaps.info/spec.html#h.mofvlxcwqzej
[`--enable-source-maps`]: cli.md#--enable-source-maps
[`NODE_V8_COVERAGE=dir`]: cli.md#node_v8_coveragedir
[`SourceMap`]: #class-modulesourcemap
[`module`]: modules.md#the-module-object
[module wrapper]: modules.md#the-module-wrapper
[source map include directives]: https://sourcemaps.info/spec.html#h.lmz475t4mvbx
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