Note: This is the first article in a series of articles where we will cover React Hooks in Depth and try to understand their usage. are a new addition in React 16.8. They let you use state and other React features without writing a class. It is a fundamental shift on how you’ll approach writing React. React Hooks Hooks do not have any breaking changes and are 100 % backward compatible. If you are a newbie learning react or seasoned pro try this! But what is a Hook? Hooks are functions that let you “hook into” React state and life-cycle features from function components. Hooks don’t work inside classes — they let you use React without classes. You can definitely mix with Hooks in a single tree. classes and function components At React Conference 2018, Sophie Alpert and Dan Abramov introduced Hooks, you can watch the video introduction below: . In the longer term, they expect Hooks to be the primary way people write React components. So, use hooks in functional components of your new project and new components of your existing project. React core team recommends Hooks in new components you write The Problems Hooks Solve Note: Hooks solve More problems, but for now we will focus on the below-mentioned ones - Functional Components can use State like class based components We can avoid writing almost the same thing in componentDidMount() and componentDidUpdate() Achieve the same functionality by writing less and much cleaner code Rules of React Hooks There are two rules that you need to follow while using React Hooks: : Don’t call Hooks inside loops, conditions, or nested functions Instead, always use Hooks at the top level of your React function. By following this rule, you ensure that Hooks are called in the same order each time a component renders. That’s what allows React to correctly preserve the state of Hooks between multiple useState and useEffect calls. Only Call Hooks at the Top Level . : Don’t call Hooks from regular JavaScript functions. Instead, you can call them from React Functions or Custom React Hooks Only Call Hooks from React Functions For more details on the rules check — https://reactjs.org/docs/hooks-rules.html#explanation React core team has provided us with a lint rule that helps us use the hooks properly (enforce the above-mentioned rules). You can also add the same in your ESLint configuration. Add the ESLint rule by doing and add this to ESLint configuration: npm install -D eslint-plugin-react-hooks { : { …, : }, : [ …, ], } "rules" "react-hooks/rules-of-hooks" "error" "plugins" "react-hooks" In the upcoming stories, we will cover the below-mentioned hooks in order: useState useEffect useContext useRef useReducer useMemo useCallback useLayoutEffect useImperativeHandle
