Why did hooks replace class components?

ReactJunior~2 min read

1. Hooks are simpler than classes

The problem with classes:

You have to understand how this works.
You often have to do method binding manually:

javascript
this.handleClick = this.handleClick.bind(this);
Errors like Cannot read property 'setState' of undefined are a common occurrence.

With hooks:

There is no this at all.
Everything is a regular function:

javascript
const [count, setCount] = useState(0);

2. Hooks make the code cleaner and more logical

The problem in classes:

Logic related to one task (for example, working with an API) is scattered across different lifecycle methods:

javascript

componentDidMount() { subscribe(); }
componentDidUpdate() { checkUpdate(); }
componentWillUnmount() { unsubscribe(); }

With hooks:

Everything is in one place:

javascript

useEffect(() => {
  subscribe();
  return () => unsubscribe();
}, []);

The code becomes more compact and logically grouped.

3. Hooks let you reuse logic

The problem with classes:

To reuse logic between components, you had to use:

HOC (Higher-Order Components) - a nesting of "wrapper hell",
or Render Props - complex JSX structures.

With hooks:

You can simply extract repeated logic into a custom hook:

javascript

function useLocalStorage(key, initialValue) {
  const [value, setValue] = useState(() =>
    JSON.parse(localStorage.getItem(key)) ?? initialValue
  );

  useEffect(() => {
    localStorage.setItem(key, JSON.stringify(value));
  }, [value]);

  return [value, setValue];
}

Used like a regular hook:

javascript

const [theme, setTheme] = useLocalStorage('theme', 'light');

4. Hooks work better with modern technologies

React hooks combine great with TypeScript, Suspense, Concurrent Rendering, Server Components.
Classes integrate poorly with newer React 18+ capabilities.
Hooks let you flexibly manage state and performance (useMemo, useCallback, useTransition).

5. Classes are harder to optimize and test

It is not always obvious when lifecycle methods get called.
Testing a class component is harder: you have to mock the instance.
Function components with hooks are just pure functions, so they are easy to test.

Summary: why React moved to hooks

Problem with classes	Solution with hooks
`this` and bind	No `this`, pure functions
Scattered lifecycle logic	useEffect combines all related logic
Hard-to-reuse logic	Custom hooks
Poor optimization and testing	Pure functions, better predictability
Poor compatibility with new React features	Full compatibility with the modern API

Conclusion: Hooks made React more declarative, functional, and modular. That is why today hooks are the standard, and classes remain only to support legacy projects.

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