React Function Component - Hooks

hooks are functions (React >= 16.8) that can be used only in a functional component

A custom Hook is a JavaScript function whose name starts with ”use” and that may call other Hooks.

Hooks are functions that let you “hook into” React state and lifecycle features from function components. Hooks don’t work inside classes

By using an hook, there is no Component to import.

https://reactjs.org/docs/hooks-rules.html

• use

See State example

Hooks let you:

• reuse logic between components without changing your component hierarchy.
• split one component into smaller functions based on what pieces are related.
• use React without classes.

React doesn’t offer a way to “attach” reusable behavior to a component (for example, connecting it to a store). If you’ve worked with React for a while, you may be familiar with patterns like render props and higher-order components that try to solve this. But these patterns require you to restructure your components

With Hooks, you can extract stateful logic from a component so it can be tested independently and reused. Hooks allow you to reuse stateful logic without changing your component hierarchy. This makes it easy to share Hooks among many components.

Each lifecycle method often contains a mix of unrelated logic such as:

• React Class Component - Fetch (Ajax)
• sets up event listeners, with cleanup

Hooks let you split one component into smaller functions based on what pieces are related (such as setting up a subscription or fetching data), rather than forcing a split based on lifecycle methods.

React Function Component - (Side) Effect (useEffect Hook)

In the log, you may see this error:

Hooks can only be called inside of the body of a function component. This could happen for one of the following reasons:
1. You might have mismatching versions of React and the renderer (such as React DOM)
2. You might be breaking the Rules of Hooks
3. You might have more than one copy of React in the same app

The invalid-hook-call gives more information but forgot to mean what it means to be inside the body of a function component.

A React component function is not just a Javascript function, this is a function wrapped in a element

If you have tried all solution and that it's not working, wrap it in a react element like that:

let App = React.createElement(yourfunction, props, ...children);

• Rfc that leads to https://github.com/reactjs/rfcs/blob/master/text/0068-react-hooks.md
• https://reactjs.org/docs/hooks-intro.html
• https://reactjs.org/docs/hooks-overview.html - Getting started