elastic
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.
Also supports hooking into calls to process.getBuiltinModule(), which was introduced in Node.js v22.3.0.
Installation
npm install require-in-the-middle --saveUsage
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 theonrequirecallback. 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 theonrequirecallback is called. If specified, this must be the second argument.options.internals<boolean> Specifies whetheronrequireshould be called when module-internal files are loaded; defaults tofalse.
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 themodule.exportsproperty that would normally be exposed by the required module.name<string> The name of the module being required. Ifoptions.internalswas set totrue, the path of module-internal files that are loaded (relative tobasedir) will be appended to the module name, separated bypath.sep.basedir<string> The directory where the module is located, orundefinedfor 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().