https://github.com/elastic/require-in-the-middle

Module to hook into the Node.js require function
https://github.com/elastic/require-in-the-middle

Last synced: 27 days ago
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Module to hook into the Node.js require function

• Host: GitHub
• URL: https://github.com/elastic/require-in-the-middle
• Owner: elastic
• License: mit
• Created: 2016-02-10T13:42:55.000Z (over 8 years ago)
• Default Branch: main
• Last Pushed: 2024-05-07T00:01:56.000Z (6 months ago)
• Last Synced: 2024-05-15T19:11:45.789Z (6 months ago)
• Language: JavaScript
• Size: 120 KB
• Stars: 158
• Watchers: 16
• Forks: 26
• Open Issues: 13
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# require-in-the-middle

Hook into the Node.js `require` function. This allows you to modify

modules on-the-fly as they are being required.

[![npm](https://img.shields.io/npm/v/require-in-the-middle.svg)](https://www.npmjs.com/package/require-in-the-middle)

[![Test status](https://github.com/elastic/require-in-the-middle/workflows/Test/badge.svg)](https://github.com/elastic/require-in-the-middle/actions)

Also supports hooking into calls to `process.getBuiltinModule()`, which was introduced in Node.js v22.3.0.

## Installation

```

npm install require-in-the-middle --save

```

## Usage

```js

const path = require('path')

const { Hook } = require('require-in-the-middle')

// Hook into the express and mongodb module

new Hook(['express', 'mongodb'], function (exports, name, basedir) {

  const version = require(path.join(basedir, 'package.json')).version

  console.log('loading %s@%s', name, version)

  // expose the module version as a property on its exports object

  exports._version = version

  // whatever you return will be returned by `require`

  return exports

})

```

## API

The require-in-the-middle module exposes a single function:

### `hook = new Hook([modules][, options], onrequire)`

When called a `hook` object is returned.

Arguments:

- `modules` <string[]> An optional array of module names to limit which modules

  trigger a call of the `onrequire` callback. If specified, this must be the

  first argument. Both regular modules (e.g. `react-dom`) and

  sub-modules (e.g. `react-dom/server`) can be specified in the array.

- `options` <Object> An optional object containing fields that change when the

  `onrequire` callback is called. If specified, this must be the second

  argument.

  - `options.internals` <boolean> Specifies whether `onrequire` should be called

    when module-internal files are loaded; defaults to `false`.

- `onrequire` <Function> The function to call when a module is required.

The `onrequire` callback will be called the first time a module is

required. The function is called with three arguments:

- `exports` <Object> The value of the `module.exports` property that would

  normally be exposed by the required module.

- `name` <string> The name of the module being required. If `options.internals`

  was set to `true`, the path of module-internal files that are loaded

  (relative to `basedir`) will be appended to the module name, separated by

  `path.sep`.

- `basedir` <string> The directory where the module is located, or `undefined`

  for core modules.

Return the value you want the module to expose (normally the `exports`

argument).

### `hook.unhook()`

Removes the `onrequire` callback so that it will not be triggerd by

subsequent calls to `require()` or `process.getBuiltinModule()`.

## License

[MIT](https://github.com/elastic/require-in-the-middle/blob/master/LICENSE)