---
parts:
  - Principles
  - Subclasser apis
title: 'Principles: Subclasser apis'
eleventyNavigation:
  key: 'Principles: Subclasser apis'
  order: 50
  parent: Principles
  title: Subclasser apis
---

# Principles: Subclasser apis

In order to make it easy for Subclassers to extend our components, we follow a certain set
of best practices naming conventions to make our code predictable.

## Templates

### Template naming conventions

For templates that do need access to the instance of the web component there is a prefix `_render/__render`.
Examples are `__renderHeader` and `__renderData`.

### Separation of concerns

Our components should make it possible to override markup and styling, without having to redefine
functionality.
By using the spread directive, we can achieve this. For more info, see [explanation](https://github.com/ing-bank/lion/issues/591).

## Node references

As a Subclasser, you sometimes need access to a protected node inside the shadow dom.
Most functional nodes have their own getters. A Subclasser can access those in his extension and
in some cases, override these getters.

### Node naming conventions

A node reference will have an underscore prefix and always ends with `Node`.
Examples are `_inputNode` and `_formNode`.
