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doc: fix module.md headings #56131

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340 changes: 170 additions & 170 deletions doc/api/module.md
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Original file line number Diff line number Diff line change
Expand Up @@ -64,159 +64,6 @@
const siblingModule = require('./sibling-module');
```

### `module.constants.compileCacheStatus`

<!-- YAML
added: v22.8.0
-->

> Stability: 1.1 - Active Development

The following constants are returned as the `status` field in the object returned by
[`module.enableCompileCache()`][] to indicate the result of the attempt to enable the
[module compile cache][].

<table>
<tr>
<th>Constant</th>
<th>Description</th>
</tr>
<tr>
<td><code>ENABLED</code></td>
<td>
Node.js has enabled the compile cache successfully. The directory used to store the
compile cache will be returned in the <code>directory</code> field in the
returned object.
</td>
</tr>
<tr>
<td><code>ALREADY_ENABLED</code></td>
<td>
The compile cache has already been enabled before, either by a previous call to
<code>module.enableCompileCache()</code>, or by the <code>NODE_COMPILE_CACHE=dir</code>
environment variable. The directory used to store the
compile cache will be returned in the <code>directory</code> field in the
returned object.
</td>
</tr>
<tr>
<td><code>FAILED</code></td>
<td>
Node.js fails to enable the compile cache. This can be caused by the lack of
permission to use the specified directory, or various kinds of file system errors.
The detail of the failure will be returned in the <code>message</code> field in the
returned object.
</td>
</tr>
<tr>
<td><code>DISABLED</code></td>
<td>
Node.js cannot enable the compile cache because the environment variable
<code>NODE_DISABLE_COMPILE_CACHE=1</code> has been set.
</td>
</tr>
</table>

### `module.enableCompileCache([cacheDir])`

<!-- YAML
added: v22.8.0
-->

> Stability: 1.1 - Active Development

* `cacheDir` {string|undefined} Optional path to specify the directory where the compile cache
will be stored/retrieved.
* Returns: {Object}
* `status` {integer} One of the [`module.constants.compileCacheStatus`][]
* `message` {string|undefined} If Node.js cannot enable the compile cache, this contains
the error message. Only set if `status` is `module.constants.compileCacheStatus.FAILED`.
* `directory` {string|undefined} If the compile cache is enabled, this contains the directory
where the compile cache is stored. Only set if `status` is
`module.constants.compileCacheStatus.ENABLED` or
`module.constants.compileCacheStatus.ALREADY_ENABLED`.

Enable [module compile cache][] in the current Node.js instance.

If `cacheDir` is not specified, Node.js will either use the directory specified by the
[`NODE_COMPILE_CACHE=dir`][] environment variable if it's set, or use
`path.join(os.tmpdir(), 'node-compile-cache')` otherwise. For general use cases, it's
recommended to call `module.enableCompileCache()` without specifying the `cacheDir`,
so that the directory can be overridden by the `NODE_COMPILE_CACHE` environment
variable when necessary.

Since compile cache is supposed to be a quiet optimization that is not required for the
application to be functional, this method is designed to not throw any exception when the
compile cache cannot be enabled. Instead, it will return an object containing an error
message in the `message` field to aid debugging.
If compile cache is enabled successfully, the `directory` field in the returned object
contains the path to the directory where the compile cache is stored. The `status`
field in the returned object would be one of the `module.constants.compileCacheStatus`
values to indicate the result of the attempt to enable the [module compile cache][].

This method only affects the current Node.js instance. To enable it in child worker threads,
either call this method in child worker threads too, or set the
`process.env.NODE_COMPILE_CACHE` value to compile cache directory so the behavior can
be inherited into the child workers. The directory can be obtained either from the
`directory` field returned by this method, or with [`module.getCompileCacheDir()`][].

#### Module compile cache

<!-- YAML
added: v22.1.0
changes:
- version: v22.8.0
pr-url: https://github.com/nodejs/node/pull/54501
description: add initial JavaScript APIs for runtime access.
-->

The module compile cache can be enabled either using the [`module.enableCompileCache()`][]
method or the [`NODE_COMPILE_CACHE=dir`][] environment variable. After it is enabled,
whenever Node.js compiles a CommonJS or a ECMAScript Module, it will use on-disk
[V8 code cache][] persisted in the specified directory to speed up the compilation.
This may slow down the first load of a module graph, but subsequent loads of the same module
graph may get a significant speedup if the contents of the modules do not change.

To clean up the generated compile cache on disk, simply remove the cache directory. The cache
directory will be recreated the next time the same directory is used for for compile cache
storage. To avoid filling up the disk with stale cache, it is recommended to use a directory
under the [`os.tmpdir()`][]. If the compile cache is enabled by a call to
[`module.enableCompileCache()`][] without specifying the directory, Node.js will use
the [`NODE_COMPILE_CACHE=dir`][] environment variable if it's set, or defaults
to `path.join(os.tmpdir(), 'node-compile-cache')` otherwise. To locate the compile cache
directory used by a running Node.js instance, use [`module.getCompileCacheDir()`][].

Currently when using the compile cache with [V8 JavaScript code coverage][], the
coverage being collected by V8 may be less precise in functions that are
deserialized from the code cache. It's recommended to turn this off when
running tests to generate precise coverage.

The enabled module compile cache can be disabled by the [`NODE_DISABLE_COMPILE_CACHE=1`][]
environment variable. This can be useful when the compile cache leads to unexpected or
undesired behaviors (e.g. less precise test coverage).

Compilation cache generated by one version of Node.js can not be reused by a different
version of Node.js. Cache generated by different versions of Node.js will be stored
separately if the same base directory is used to persist the cache, so they can co-exist.

At the moment, when the compile cache is enabled and a module is loaded afresh, the
code cache is generated from the compiled code immediately, but will only be written
to disk when the Node.js instance is about to exit. This is subject to change. The
[`module.flushCompileCache()`][] method can be used to ensure the accumulated code cache
is flushed to disk in case the application wants to spawn other Node.js instances
and let them share the cache long before the parent exits.

### `module.getCompileCacheDir()`

<!-- YAML
added: v22.8.0
-->

> Stability: 1.1 - Active Development

* Returns: {string|undefined} Path to the [module compile cache][] directory if it is enabled,
or `undefined` otherwise.

### `module.findPackageJSON(specifier[, base])`

<!-- YAML
Expand Down Expand Up @@ -352,7 +199,7 @@
Register a module that exports [hooks][] that customize Node.js module
resolution and loading behavior. See [Customization hooks][].

## `module.stripTypeScriptTypes(code[, options])`
### `module.stripTypeScriptTypes(code[, options])`

<!-- YAML
added: v23.2.0
Expand Down Expand Up @@ -490,6 +337,175 @@
});
```

## Module compile cache

<!-- YAML
added: v22.1.0
changes:
- version: v22.8.0
pr-url: https://github.com/nodejs/node/pull/54501

Check warning on line 346 in doc/api/module.md

View workflow job for this annotation

GitHub Actions / lint-pr-url 

pr-url doesn't match the URL of the current PR.
description: add initial JavaScript APIs for runtime access.
-->

The module compile cache can be enabled either using the [`module.enableCompileCache()`][]
method or the [`NODE_COMPILE_CACHE=dir`][] environment variable. After it is enabled,
whenever Node.js compiles a CommonJS or a ECMAScript Module, it will use on-disk
[V8 code cache][] persisted in the specified directory to speed up the compilation.
This may slow down the first load of a module graph, but subsequent loads of the same module
graph may get a significant speedup if the contents of the modules do not change.

To clean up the generated compile cache on disk, simply remove the cache directory. The cache
directory will be recreated the next time the same directory is used for for compile cache
storage. To avoid filling up the disk with stale cache, it is recommended to use a directory
under the [`os.tmpdir()`][]. If the compile cache is enabled by a call to
[`module.enableCompileCache()`][] without specifying the directory, Node.js will use
the [`NODE_COMPILE_CACHE=dir`][] environment variable if it's set, or defaults
to `path.join(os.tmpdir(), 'node-compile-cache')` otherwise. To locate the compile cache
directory used by a running Node.js instance, use [`module.getCompileCacheDir()`][].

Currently when using the compile cache with [V8 JavaScript code coverage][], the
coverage being collected by V8 may be less precise in functions that are
deserialized from the code cache. It's recommended to turn this off when
running tests to generate precise coverage.

The enabled module compile cache can be disabled by the [`NODE_DISABLE_COMPILE_CACHE=1`][]
environment variable. This can be useful when the compile cache leads to unexpected or
undesired behaviors (e.g. less precise test coverage).

Compilation cache generated by one version of Node.js can not be reused by a different
version of Node.js. Cache generated by different versions of Node.js will be stored
separately if the same base directory is used to persist the cache, so they can co-exist.

At the moment, when the compile cache is enabled and a module is loaded afresh, the
code cache is generated from the compiled code immediately, but will only be written
to disk when the Node.js instance is about to exit. This is subject to change. The
[`module.flushCompileCache()`][] method can be used to ensure the accumulated code cache
is flushed to disk in case the application wants to spawn other Node.js instances
and let them share the cache long before the parent exits.

### `module.constants.compileCacheStatus`

<!-- YAML
added: v22.8.0
-->

> Stability: 1.1 - Active Development

The following constants are returned as the `status` field in the object returned by
[`module.enableCompileCache()`][] to indicate the result of the attempt to enable the
[module compile cache][].

<table>
<tr>
<th>Constant</th>
<th>Description</th>
</tr>
<tr>
<td><code>ENABLED</code></td>
<td>
Node.js has enabled the compile cache successfully. The directory used to store the
compile cache will be returned in the <code>directory</code> field in the
returned object.
</td>
</tr>
<tr>
<td><code>ALREADY_ENABLED</code></td>
<td>
The compile cache has already been enabled before, either by a previous call to
<code>module.enableCompileCache()</code>, or by the <code>NODE_COMPILE_CACHE=dir</code>
environment variable. The directory used to store the
compile cache will be returned in the <code>directory</code> field in the
returned object.
</td>
</tr>
<tr>
<td><code>FAILED</code></td>
<td>
Node.js fails to enable the compile cache. This can be caused by the lack of
permission to use the specified directory, or various kinds of file system errors.
The detail of the failure will be returned in the <code>message</code> field in the
returned object.
</td>
</tr>
<tr>
<td><code>DISABLED</code></td>
<td>
Node.js cannot enable the compile cache because the environment variable
<code>NODE_DISABLE_COMPILE_CACHE=1</code> has been set.
</td>
</tr>
</table>

### `module.enableCompileCache([cacheDir])`

<!-- YAML
added: v22.8.0
-->

> Stability: 1.1 - Active Development

* `cacheDir` {string|undefined} Optional path to specify the directory where the compile cache
will be stored/retrieved.
* Returns: {Object}
* `status` {integer} One of the [`module.constants.compileCacheStatus`][]
* `message` {string|undefined} If Node.js cannot enable the compile cache, this contains
the error message. Only set if `status` is `module.constants.compileCacheStatus.FAILED`.
* `directory` {string|undefined} If the compile cache is enabled, this contains the directory
where the compile cache is stored. Only set if `status` is
`module.constants.compileCacheStatus.ENABLED` or
`module.constants.compileCacheStatus.ALREADY_ENABLED`.

Enable [module compile cache][] in the current Node.js instance.

If `cacheDir` is not specified, Node.js will either use the directory specified by the
[`NODE_COMPILE_CACHE=dir`][] environment variable if it's set, or use
`path.join(os.tmpdir(), 'node-compile-cache')` otherwise. For general use cases, it's
recommended to call `module.enableCompileCache()` without specifying the `cacheDir`,
so that the directory can be overridden by the `NODE_COMPILE_CACHE` environment
variable when necessary.

Since compile cache is supposed to be a quiet optimization that is not required for the
application to be functional, this method is designed to not throw any exception when the
compile cache cannot be enabled. Instead, it will return an object containing an error
message in the `message` field to aid debugging.
If compile cache is enabled successfully, the `directory` field in the returned object
contains the path to the directory where the compile cache is stored. The `status`
field in the returned object would be one of the `module.constants.compileCacheStatus`
values to indicate the result of the attempt to enable the [module compile cache][].

This method only affects the current Node.js instance. To enable it in child worker threads,
either call this method in child worker threads too, or set the
`process.env.NODE_COMPILE_CACHE` value to compile cache directory so the behavior can
be inherited into the child workers. The directory can be obtained either from the
`directory` field returned by this method, or with [`module.getCompileCacheDir()`][].

### `module.flushCompileCache()`

<!-- YAML
added:
- v23.0.0
- v22.10.0
-->

> Stability: 1.1 - Active Development

Flush the [module compile cache][] accumulated from modules already loaded
in the current Node.js instance to disk. This returns after all the flushing
file system operations come to an end, no matter they succeed or not. If there
are any errors, this will fail silently, since compile cache misses should not
interfere with the actual operation of the application.

### `module.getCompileCacheDir()`

<!-- YAML
added: v22.8.0
-->

> Stability: 1.1 - Active Development

* Returns: {string|undefined} Path to the [module compile cache][] directory if it is enabled,
or `undefined` otherwise.

<i id="module_customization_hooks"></i>

## Customization Hooks
Expand Down Expand Up @@ -1285,22 +1301,6 @@
`path` is the resolved path for the file for which a corresponding source map
should be fetched.

### `module.flushCompileCache()`

<!-- YAML
added:
- v23.0.0
- v22.10.0
-->

> Stability: 1.1 - Active Development

Flush the [module compile cache][] accumulated from modules already loaded
in the current Node.js instance to disk. This returns after all the flushing
file system operations come to an end, no matter they succeed or not. If there
are any errors, this will fail silently, since compile cache misses should not
interfere with the actual operation of the application.

### Class: `module.SourceMap`

<!-- YAML
Expand Down
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