ALL React Hooks Explained in 12 Minutes

Summary

The video organizes React Hooks into eight categories and explains what each hook does, when it is useful, and how often most developers are likely to need it. Its main lesson is to choose a hook for a specific purpose rather than using hooks indiscriminately.

1. State management

• useState — used frequently: Stores a component’s state and returns the current value and a function to update it. Common uses include form inputs, showing or hiding UI, conditional styling, counters, and shopping-cart quantities.
• useReducer — used occasionally: Handles more complex or related state through a reducer function. Calling dispatch sends an action to the reducer, which decides how the state changes. It can simplify components with multiple related values or interactions.
• useSyncExternalStore — rarely used by typical app developers: Connects a component to a state store outside React. It is mainly relevant when building a state-management library or integrating an external store.

2. Effects and synchronization

Effects let React coordinate with systems outside React, such as browser APIs.

• useEffect — used selectively: Runs after the UI renders. A dependency array controls when it runs. The video cautions against using it for work that belongs elsewhere:
  • Put event-driven actions, such as responding to a button click, directly in the event handler.
  • Prefer dedicated data-fetching tools or framework patterns over fetching data in an effect when a component mounts.
  • Use it when React needs to synchronize with an external system, such as a browser media API.
• useLayoutEffect — used even less often: Runs synchronously before the browser paints the UI. It is useful when something must be measured or updated before it becomes visible—for example, measuring a tooltip and setting its position.
• useInsertionEffect — highly specialized: Intended mainly for CSS-in-JS library authors. It runs early so styles can be inserted before other effects need to read layout information.

3. Refs and imperative access

• useRef — useful for values that should persist without triggering a render: Its value is accessed through .current and can be changed directly. Refs can hold values such as a timer ID or provide access to a DOM element.
• useImperativeHandle — rarely used: Lets a child component expose selected methods through a ref, such as allowing a parent to focus an input inside the child. The example also uses forwardRef; the video notes that forwarding refs will not be required in React 19.

4. Performance and memoization

• useMemo: Caches the result of a calculation and recomputes it when a dependency changes. It is intended for expensive computations, not side effects.
• useCallback: Caches a function, often one passed as a prop to a child component, so it is not recreated on every render.

Both hooks are presented as performance tools to use when there is a relevant performance concern.

5. Context

• useContext: Reads a value supplied by a context provider. Any component nested within that provider can access the value, even when deeply nested.

6. Transitions and deferred updates

• useTransition: Marks certain state updates as non-urgent so the interface can stay responsive during heavier work, such as filtering a large list while a user types. It also provides an isPending value that can be used to show a loading state.
• useDeferredValue: Lets React defer updating a value until a suitable time. It can support responsive interfaces, such as during list filtering, without manually starting a transition or tracking pending state.

7. Other specialized hooks

• useDebugValue: Labels a custom hook’s value in React DevTools. It is mainly useful to developers who regularly inspect custom hooks with those tools.
• useId: Generates IDs for relationships such as form inputs and their labels, including when a component is used multiple times on a page. The video explicitly warns against using it to generate list keys.

Speakers and sources mentioned

• Speaker: One unnamed narrator/presenter from Code Bootcamp.
• Tools, libraries, and technologies: React, React 19, React DevTools, React Query, Next.js, styled-components, Framer Motion, and browser APIs, including the document and media APIs.
• Promotional resources: The presenter’s React Bootcamp course and a separate video about React 19 hooks.