


Write a custom hook to track the window size and update a component when it changes.
Mar 26, 2025 pm 06:27 PMWrite a custom hook to track the window size and update a component when it changes.
To create a custom hook that tracks the window size and updates a component when it changes, we'll use the useState
and useEffect
hooks in React. Here's a step-by-step approach to implementing this hook:
import { useState, useEffect } from 'react'; function useWindowSize() { // Initialize state with undefined width/height so server-side render works const [windowSize, setWindowSize] = useState({ width: undefined, height: undefined, }); useEffect(() => { // Handler to call on window resize function handleResize() { // Set window width/height to state setWindowSize({ width: window.innerWidth, height: window.innerHeight, }); } // Add event listener window.addEventListener("resize", handleResize); // Call handler right away so state gets updated with initial window size handleResize(); // Remove event listener on cleanup return () => window.removeEventListener("resize", handleResize); }, []); // Empty array ensures that effect is only run on mount return windowSize; } export default useWindowSize;
This custom hook, useWindowSize
, uses the useState
hook to manage the state of the window size and the useEffect
hook to set up and clean up the event listener for the window's resize event. The hook returns the current window size, which can be used in any component that imports and uses this hook.
How can I implement a custom hook to monitor window size changes in real-time?
To implement a custom hook for monitoring window size changes in real-time, follow these steps:
- Import Necessary Hooks: Start by importing
useState
anduseEffect
from React, as these are essential for managing state and side effects. - Initialize State: Use
useState
to initialize the state withwidth
andheight
set toundefined
. This allows the hook to work correctly during server-side rendering wherewindow
might not be available. - Create a Resize Handler: Define a function
handleResize
that updates the state with the currentwindow.innerWidth
andwindow.innerHeight
. - Set Up Event Listener: Inside
useEffect
, add an event listener to thewindow
object for theresize
event. This listener will callhandleResize
whenever the window is resized. - Initial Call: Immediately call
handleResize
withinuseEffect
to set the initial window size. - Cleanup: Return a cleanup function from
useEffect
that removes the event listener when the component unmounts or the effect runs again. - Return State: Finally, return the
windowSize
state from the hook so it can be used in components.
This approach ensures that the hook updates the window size in real-time and cleans up resources appropriately.
What are the best practices for using a custom hook to efficiently update components based on window size?
When using a custom hook to update components based on window size, consider the following best practices:
- Optimize Performance: Use
useMemo
oruseCallback
to memoize expensive computations or callback functions that depend on the window size. This prevents unnecessary re-renders. - Debounce Resize Events: To prevent excessive updates during rapid resizing, consider debouncing the resize event handler. Libraries like
lodash.debounce
can be useful for this purpose. - Conditional Rendering: Use the window size to conditionally render different layouts or components. This can improve the user experience by adapting the UI to different screen sizes.
- Server-Side Rendering Compatibility: Ensure your hook works with server-side rendering by initializing state with
undefined
values and checking for the existence ofwindow
before accessing it. - Cleanup: Always clean up event listeners in the
useEffect
cleanup function to prevent memory leaks. - Reusability: Design your hook to be reusable across different components and projects. Keep it focused on a single responsibility (in this case, tracking window size).
- Testing: Write tests for your custom hook to ensure it behaves correctly under various conditions, including different window sizes and during component lifecycle events.
Can you provide an example of how to integrate a window size tracking hook into an existing React component?
Here's an example of how to integrate the useWindowSize
hook into an existing React component:
import React from 'react'; import useWindowSize from './useWindowSize'; // Assuming the hook is in a separate file function MyComponent() { const { width, height } = useWindowSize(); return ( <div> <h1>Current Window Size</h1> <p>Width: {width}px</p> <p>Height: {height}px</p> {width > 768 ? ( <p>This is a wide screen layout</p> ) : ( <p>This is a narrow screen layout</p> )} </div> ); } export default MyComponent;
In this example, MyComponent
uses the useWindowSize
hook to get the current window dimensions. It then displays these dimensions and uses them to conditionally render different content based on the window width. This demonstrates how the hook can be easily integrated into a component to dynamically update the UI based on the window size.
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