---
lang: en
title: 'Language-related concepts'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
permalink: /doc/en/lb4/Language-related-concepts.html
---

A module that exports JavaScript/TypeScript concept related functions.

- [**Mixin**](Mixin.md): Add properties and methods to a class.
