The introduction of Hooks in version 16.8 completely transformed the way we build applications in React. This change allowed functional components to fully manage state and the lifecycle, something that was previously reserved exclusively for class components. If you want to understand, How do hooks work in React: useState and useEffect?, you need to view them not as magic, but as powerful tools that make use of JavaScript’s closure mechanism.
What are Hooks and why were they created?
Hooks are special functions that „hook into” (. hook) on internal mechanisms Reacta. Their main purpose is to enable the reuse of state logic between components without having to change their structure. This makes the code flatter, more readable and easier to test.
Before you move on to advanced techniques, it’s worth refreshing your knowledge of the library’s basics in our article: React – from the basics to advanced concepts.
useState: Managing local state
This is the most commonly used hook. It allows you to add state to a functional component. Calling useState returns an array containing two elements: the current state value and a function that updates it.
Key principles of useState:
- Initialisation: You can pass the initial value directly or via a function (lazy initialisation).
- Asynchrony: Please note that state updates do not happen instantly – React queues changes to optimise performance.
useEffect: Managing side effects
Understanding this, How do hooks work in React: useState and useEffect?, ... is impossible without mastering useEffect. It is used to perform operations such as fetching data from an API, managing subscriptions, or manually modifying the DOM. It replaces the lifecycle methods found in the following classes: componentDidMount, componentDidUpdate and componentWillUnmount.
The anatomy of useEffect:
- Effect function: The code to be executed.
- Dependency table: Determines when the effect should be restarted. An empty array
[]will ensure that the effect is applied only once (during installation). - Cleanup function: An optional function returned by the effect, which cleans up after timers or subscriptions, for example, to prevent memory leaks.
Advanced Hooks: Context, Reducer and Memoisation
As your app grows, useState i useEffect may not be enough. React offers a set of tools for more complex tasks:
- useContext: It allows you to use the global state without having to pass it on props through multiple component levels (prop drilling). You can find out more about choosing tools here: State management – Redux vs Zustand vs Context.
- useReducer: The perfect alternative to
useState, when the state logic is complex and depends on previous values. It works in a similar way to the Redux pattern. - useRef: Provides access to DOM elements or stores mutable values that do not trigger a re-render of the component when changed.
- useMemo and useCallback: Optimisation tools. These are used to cache the results of computationally intensive calculations or function definitions in order to avoid unnecessary re-renders.
Custom Hooks: Extracting shared logic
React’s greatest strength is the ability to create your own hooks. If you notice that the same logic (e.g. fetching data, handling a form, tracking mouse position) is repeated across several components, you can wrap it in a function starting with the word use.
Custom hooks allow you to clearly separate business logic from the presentation layer. You can find ready-made solutions and inspiration on the website useHooks.com.
Summary: Writing Modern React
Knowing this, How do hooks work in React: useState and useEffect?, ...is the absolute cornerstone of a modern front-end developer’s work in 2026. Hooks have made React more functional, elegant and less repetitive. The key to success is understanding that hooks must always be called in the same order and only at the top level of the component function.
At 4ADStudio, we build high-performance applications based on the latest React standards. We ensure that every line of code is optimised and easy to maintain.
Is your React project becoming too complex? Are you experiencing performance issues and unnecessary renders? Get in touch with us – our experts will help you optimise your application’s architecture and implement best practices for working with hooks!
