---
title: React Component with Dot Notation
date: 2019-02-19 11:45:47 +07:00
tags: [react, javascript, dot-notation]
layout: post  
thumbnail: https://media.giphy.com/media/dIxkmtCuuBQuM9Ux1E/200w_d.gif
---

This is my answer to someone’s question on [StackOverflow](https://stackoverflow.com/questions/49256472/react-how-to-extend-a-component-that-has-child-components-and-keep-them/49258038#answer-49258038). How can we define a React component that is accessible through the dot notation?

Take a look at the following code. We have the ```Menu``` component and its three children ```Menu.Item:```

    const App = () => (
      <Menu>
        <Menu.Item>Home</Menu.Item>
        <Menu.Item>Blog</Menu.Item>
        <Menu.Item>About</Menu.Item>
      </Menu>
    );

How can we define a component like ```Menu```? Where it has some kind of “sub-component” that is accessible through a dot notation.

Well, it’s actually a pretty common pattern. And it’s not really a sub-component, it’s just another component being attached to another one.

Let’s use the above ```Menu```component for example. We’ll put this component to its own dedicated file: ```menu.js```. First, let’s define these two components separately on this module file:

    // menu.js
    import React from 'react';

    export const MenuItem = ({ children }) => <li>{children}</li>;

    export default const Menu = ({ children }) => <ul>{children}</ul>;

It’s just a simple functional component. The ```Menu``` is the parent with ```ul``` tag. And the ```MenuItem``` will act as its children. Now we can use these two components like so:

    import React from 'react';
    import { render } from 'react-dom';
    import Menu, { MenuItem } from './menu';

    const App = () => (
      <Menu>
        <MenuItem>Home</MenuItem>
        <MenuItem>Blog</MenuItem>
        <MenuItem>About</MenuItem>
      </Menu>
    );

    render(<App />, document.getElementById('root'));

Where’s the dot notation? To make our MenuItem component accessible through the dot nation, we can simply attach it to the Menu component as a static property. To do so, we can no longer use the functional component for Menu and switch to the class component instead:

    // menu.js
    import React, { Component } from 'react';

    export default const MenuItem = ({ children }) => <li>{children}</li>;

    export default class Menu extends Component {
      static Item = MenuItem;

      render() {
        return (
          <ul>{this.props.children}</ul>
        );
      }
    }

Now we can use the dot notation to declare the ```MenuItem``` component:

    import React from 'react';
    import { render } from 'react-dom';
    import Menu from './menu';

    const App = () => (
      <Menu>
        <Menu.Item>Home</Menu.Item>
        <Menu.Item>Blog</Menu.Item>
        <Menu.Item>About</Menu.Item>
      </Menu>
    );

    render(<App />, document.getElementById('root'));

You can also put the ```MenuItem``` component definition directly within the ```Menu``` class. But this way you can no longer import ```MenuItem``` individually.

    import React, { Component } from 'react';

    export default class Menu extends Component {
      static Item = ({ children }) => <li>{children}</li>;

      render() {
        return (
          <ul>{this.props.children}</ul>
        );
      }
    }

**For demo purpose**, Originally published at <https://bagja.net>.