@openreachtech/mentsu-mixin-builder

Builds a mixin-extended object by layering mixin objects on top of a root object.

Concept

MixinBuilder takes a root object and any number of mixin objects, and produces a single object that exposes the members of all of them.

Property access on the built object resolves to the first target that defines the property, in the order root → mixins (in the order they were added). Methods keep this bound to the built object, so a method borrowed from one mixin can read properties provided by another.

Installation

Requires Node.js 20.x (the version the CI builds against).

npm install @openreachtech/mentsu-mixin-builder

When using GitHub Packages (the @openreachtech scope), the following two items are required:

1. Add the registry to your project's .npmrc:

   @openreachtech:registry=https://npm.pkg.github.com

2. Authenticate with npm login:

   npm login --registry https://npm.pkg.github.com

It is an ES module ("type": "module"); import it with ESM import syntax.

Usage

import MixinBuilder from '@openreachtech/mentsu-mixin-builder'

const rootTarget = {
  greet () {
    return `Hello, ${this.name}`
  },
}

const alphaMixin = {
  name: 'Alpha',
}

const betaMixin = {
  farewell () {
    return `Bye, ${this.name}`
  },
}

const built = MixinBuilder.create({ root: rootTarget })
  .addMixins(alphaMixin, betaMixin)
  .build()

built.greet()    // "Hello, Alpha"   (greet from root, name from alphaMixin)
built.farewell() // "Bye, Alpha"     (farewell from betaMixin, name from alphaMixin)

API

Class members are written with the following notation.

| notation | members | | :-- | :-- | | #instanceProperty | instance property | | #instanceMethod() | instance method | | #get:instanceGetter | instance getter | | #set:instanceSetter | instance setter | | .staticProperty | static property | | .staticMethod() | static method | | .get:staticGetter | static getter | | .set:staticSetter | static setter |

.create({ root })

Factory method. Creates a MixinBuilder for the given root object.

• root — The base object to be extended. Defaults to {}.
• Returns a MixinBuilder instance.

#addMixins(...objects)

Adds mixin objects to layer on top of the root. Chainable.

• ...objects — Mixin objects to add.
• Returns the same MixinBuilder (for method chaining).

#build()

Builds and returns the mixin-extended object.

• Returns the extended object. Property access resolves to the first target that defines the property, in the order root → mixins.

Contribution

Bug reports, feature requests, and code contributions are welcome.

Feel free to contact us through GitHub Issues.

git clone https://github.com/openreachtech/mentsu-mixin-builder.git
cd mentsu-mixin-builder
npm install
npm run lint
npm test

License

This project is released under the Apache License 2.0.

For more details, please see in the LICENSE file.

Developer

Open Reach Tech Inc.

Copyright

© 2026 Open Reach Tech Inc.