Functional Components — JS: React

You don't have to use classes to create React components. In cases where the component doesn't have a state, it's much easier to use an alternative method.

See the Pen js_react_functional_components by Hexlet (@hexlet) on CodePen.

Components created as functions are called functional components. They take an object with properties as their first argument, and also start with a capital letter.

You'll no doubt be asking when they should be used. The answer is very simple. You should always use it when a component doesn't store a state in itself. In other words, most of the components in the project should be functional.

Otherwise, they behave exactly the same as class components.

Namespaces

Remember the example from the last lesson involving the use of child components created specifically for parent components:

<Card>
  <CardTitle>Title</CardTitle>
  <CardBody>
    <b>Body</b>
  </CardBody>
</Card>

Based on the above, the components <CardTitle> and <CardBody> must be implemented as functional components.

But that's not all, you can go further and implement this structure:

import Card from './Card.jsx';

<Card>
  <Card.Body>
    <Card.Title>Title</Card.Title>
  </Card.Body>
</Card>

JSX supports the namespace mechanism. That's not to say you can't live without it, but it's quite useful. Firstly, you only need to import the top-level component, and the rest is available through it, which makes sense if you look at JSX as JS code. Secondly, this way the semantics are set better.

This mechanism is implemented through static properties.

See the Pen js_react_functional_components_namespaces by Hexlet (@hexlet) on CodePen.

This layout method doesn't require all the components to be created in the same file. The structure can be anything, and imports can cover the rest.

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