React Hookable Component

Use hooks in class-based components.

Simply replace extends Component or extends PureComponent with extends HookableComponent or extends HookablePureComponent. You can then use hooks in the render() method.

import { HookableComponent } from 'react-hookable-component';

//                                  👇👇👇👇👇👇👇👇
class ComponentThatUsesHook extends HookableComponent<Props, State> {
	render() {
		//            👇👇👇👇👇👇
		const value = useSomeHook();
		return <span>The value is {value}</span>;
	}
}

Limitations

• UNSAFE_componentWillUpdate is not called for update triggered via hooks.
• Hooks only work in render() method. (But you can save the result to a field in this and use that from elsewhere.)
• render() must be a class method defined in the prototype.

// ✅ This works
class MyComponent extends HookableComponent<Props, State> {
	render() {
		// ...
	}
}

// ❌ This doesn't work
class MyComponent extends HookableComponent<Props, State> {
	render = () => {
		// ...
	}
}

// ❌ This also doesn't work
class MyComponent extends HookableComponent<Props, State> {
	constructor(props: Props) {
		super(props);
		this.render = () => {
			// ...
		};
	}
}

How It Works

HookableComponent turns your render() method into a functional component so hooks work. The render() method still have access to the class instance's this.

Want to know more? The code is really short, just go take a look.

Live Demo

On CodeSandbox

Common Use Recipes

Use contexts in class components

This example shows usage of two React contexts.

class MyComponent extends HookableComponent<Props, State> {
	myContextValue: null | TMyContext = null;
	render() {
		// Simply use `useContext`.
		const myContextValue = useContext(MyContext);
		// You can save it to `this` so it can be accessed by other methods later.
		this.myContextValue = myContextValue;

		// Use as many contexts as you want.
		const anotherContextValue = useContext(AnotherContext);
		// ...
	}
}

Memoize computation in class components

This example shows usage of useMemo.

class MyComponent extends HookablePureComponent<Props, State> {
	expensiveComputation = () => {
		let result = 0;
		for (let i = 0; i < 1000; i++) {
			result += this.props.computationInput;
		}
		return result;
	}
	render() {
		const expensiveAnswer = useMemo(this.expensiveComputation, [this.props.computationInput]);
		return <span>The answer is {expensiveAnswer}</span>;
	}
}

FAQ

eslint complains about using hooks in class components.

Do // eslint-disable-next-line react-hooks/rules-of-hooks.

I'm not extending Component or PureComponent, but rather my own class.

In that case you can use makeHookable instead.

import { makeHookable } from 'react-hookable-component';

class MyComponent extends MyCustomComponentClass {
	constructor(props: Props) {
		super(props);
		// ...
		makeHookable(this); // 👈 this right here at the end of constructor!
	}
}

I don't want to use hooks in class components. I would rather make hooks out of classes!

Use class-based-react-hooks.