Introducing React Hooks

Question 1

What exactly are Hooks?

Accepted Answer

Javascript functions

Answer

React Hooks are essentially JavaScript functions that allow you to 'hook into' React state and lifecycle features directly from function components. They provide a way to manage state, perform side effects, and access context without needing to write class components. Examples include `useState`, `useEffect`, and `useContext`.

Question 2

Choose which is not an in-build hook.

Accepted Answer

useFetch

Answer

Among the options, `useState`, `useRef`, and `useEffect` are all built-in React Hooks provided by the React library. `useFetch` is not a standard built-in Hook; while it's a common pattern for data fetching and often implemented as a custom hook or found in third-party libraries, it is not part of the core React API.

Question 3

When do the states initialize in lifecycles?

Accepted Answer

Mounting

Answer

In React's component lifecycle, states are initialized during the 'mounting' phase. This is the stage when a component is first created and inserted into the DOM. For instance, the `useState` hook initializes its state with the provided initial value only when the component first renders and mounts.

Question 4

Which won't force the component to re-render?

Accepted Answer

Changes in .current of useRef

Answer

Changes to the `.current` property of a `useRef` hook do not trigger a re-render of the component. `useRef` is primarily used to persist mutable values across renders or to access DOM elements directly without causing the component to update. Only changes to state, props, or the dependency array of `useEffect` (which can indirectly cause state changes) will force a component to re-render.

Question 5

ReactJS may be incorporated into any current web application.

Accepted Answer

True

Answer

ReactJS is designed for incremental adoption, meaning it can be seamlessly integrated into existing web applications without requiring a complete rewrite. You can render React components within specific parts of an existing HTML page, allowing you to gradually introduce React functionality or use it for particular UI elements alongside other technologies.

React Practice Test

React Practice Test

Introducing React Hooks