React Rerender on Browser Resize

• Introduction
• Step-by-Step Guide
• Code Example
• Additional Notes
• Summary
• Conclusion
• References

In React applications, components re-render based on state or prop changes, but not automatically when the browser window is resized. This guide provides a step-by-step approach to implement window resize event handling and trigger component re-renders accordingly using JavaScript and React hooks. We'll cover setting up state variables for window dimensions, using the useEffect hook to manage resize events, and leveraging state changes to initiate re-renders. Additionally, we'll explore considerations for performance optimization and alternative approaches using responsive design libraries.

While React efficiently manages rendering based on state and prop changes, it doesn't inherently respond to browser window resizing. To achieve this, we need to implement a mechanism to detect resize events and trigger re-renders accordingly. Here's a step-by-step breakdown using JavaScript:

1. Setting Up State and the Effect Hook:

• Import useState and useEffect: Begin by importing these hooks from the 'react' library. They are essential for managing state and side effects in functional components.

import React, { useState, useEffect } from 'react';

• Create State Variables: Define state variables to store the current window dimensions (width and height).

const [windowWidth, setWindowWidth] = useState(window.innerWidth);
const [windowHeight, setWindowHeight] = useState(window.innerHeight);

2. Handling Resize Events:

• Define a Function to Update Dimensions: Create a function that will be responsible for updating the state variables with the new window dimensions whenever a resize event occurs.

const handleResize = () => {
  setWindowWidth(window.innerWidth);
  setWindowHeight(window.innerHeight);
};

• Utilize useEffect: Employ the useEffect hook to set up a listener for the window's 'resize' event. Within the effect, add the event listener and ensure proper cleanup by removing it when the component unmounts.

useEffect(() => {
  window.addEventListener('resize', handleResize);
  return () => window.removeEventListener('resize', handleResize);
}, []);

3. Triggering Re-renders:

• Leverage State Changes: Since the handleResize function updates the state variables, React will automatically detect these changes and trigger a re-render of the component.

4. Utilizing Window Dimensions:

• Access Dimensions in JSX: You can now access the windowWidth and windowHeight state variables within your JSX to conditionally render content or apply styles based on the current window size.

return (
  <div>
    Window width: {windowWidth}px
    Window height: {windowHeight}px
    {/* Conditionally render content based on window size */}
  </div>
);

Additional Considerations:

• Performance Optimization: Frequent re-renders due to rapid resize events can impact performance. Consider using techniques like debouncing or throttling to limit the frequency of updates.
• Responsive Design Libraries: Libraries like 'react-responsive' offer convenient ways to manage responsive layouts based on breakpoints, potentially simplifying your code.

Remember: This is a basic example. You can adapt and extend this approach to fit your specific use case and complexity.

This React component demonstrates how to re-render a component when the browser window is resized. It uses the useState and useEffect hooks to track window dimensions and update the component accordingly. The code includes a resize event listener that triggers a state update, causing the component to re-render with the latest window width and height. Additionally, it showcases conditional rendering based on window size, displaying specific content only on larger screens.

import React, { useState, useEffect } from 'react';

function MyComponent() {
  const [windowWidth, setWindowWidth] = useState(window.innerWidth);
  const [windowHeight, setWindowHeight] = useState(window.innerHeight);

  const handleResize = () => {
    setWindowWidth(window.innerWidth);
    setWindowHeight(window.innerHeight);
  };

  useEffect(() => {
    window.addEventListener('resize', handleResize);
    return () => window.removeEventListener('resize', handleResize);
  }, []);

  return (
    <div>
      <h1>Current Window Dimensions:</h1>
      <p>Width: {windowWidth}px</p>
      <p>Height: {windowHeight}px</p>
      {/* Example of conditional rendering based on window width */}
      {windowWidth > 768 && <p>This content only shows on larger screens.</p>}
    </div>
  );
}

export default MyComponent;

Explanation:

1. State and Effect Hook: We import useState and useEffect from React. We then define state variables windowWidth and windowHeight to store the current window dimensions, initialized with the initial window size.

2. Resize Handler: The handleResize function updates the state variables with the new window dimensions whenever the window is resized.

3. Event Listener: Inside useEffect, we add an event listener for the 'resize' event on the window. This ensures handleResize is called whenever the window size changes. We also return a cleanup function to remove the event listener when the component unmounts, preventing memory leaks.

4. Rendering and Conditional Content: The component renders the current window dimensions and demonstrates conditional rendering based on the windowWidth. This example shows content only when the window width is greater than 768px.

Additional Considerations:

• Performance: As mentioned in the article, consider using debouncing or throttling techniques to optimize performance if you experience issues with frequent re-renders.
• Responsive Design Libraries: Explore libraries like react-responsive for more advanced and convenient ways to handle responsive layouts.

Debouncing and Throttling for Performance Optimization:

• Debouncing: This technique limits the frequency of function calls by introducing a delay. In the context of window resize, it ensures that the handleResize function is only executed after the user has finished resizing the window, preventing unnecessary re-renders during the resizing process. Libraries like lodash provide debounce utilities.
• Throttling: Throttling restricts the execution of a function to a specific interval. For window resize, it means that the handleResize function will be called at most once within a set time frame, even if the resize event fires multiple times. This helps maintain responsiveness while reducing the number of re-renders.

Responsive Design Libraries:

• react-responsive: This popular library offers a declarative way to manage responsive layouts using components like MediaQuery and useMediaQuery. It simplifies the process of applying different styles or rendering different content based on breakpoints.
• Other Options: Several other libraries provide similar functionality, such as react-media and react-device-detect. Explore and choose the one that best suits your project's needs and preferences.

CSS Media Queries:

• While the focus of this guide is on JavaScript-based solutions, remember that CSS media queries are a powerful tool for handling responsive design. They allow you to apply different styles based on screen size, orientation, and other media features directly within your CSS. Consider combining CSS media queries with JavaScript-based approaches for a comprehensive responsive design strategy.

Testing and Debugging:

• Thorough Testing: Ensure you test your resize handling logic across different browsers and devices to guarantee consistent behavior. Pay attention to edge cases and potential performance issues.
• Debugging Tools: Utilize browser developer tools to inspect resize events, track state changes, and profile performance. This can help identify and resolve any unexpected behavior or bottlenecks.

Accessibility Considerations:

• Zoom and Text Scaling: Be mindful of users who may zoom in on the page or adjust text scaling. Ensure your responsive design adapts gracefully to these changes and maintains readability and usability.
• Assistive Technologies: Consider how your responsive design interacts with assistive technologies like screen readers. Make sure the content remains accessible and navigable for all users.

In conclusion, re-rendering React components on window resize is crucial for creating responsive and dynamic user interfaces. While React's core mechanism doesn't inherently handle resize events, we can effectively implement this behavior using JavaScript and React hooks. By setting up state variables to track window dimensions, utilizing the useEffect hook to manage resize events, and leveraging state changes to trigger re-renders, we can ensure our components adapt seamlessly to different screen sizes.

Furthermore, it's essential to consider performance optimization techniques like debouncing or throttling to prevent excessive re-renders and maintain a smooth user experience. Additionally, exploring responsive design libraries such as react-responsive can provide convenient and declarative ways to manage complex responsive layouts.

Remember to test your resize handling logic thoroughly across various browsers and devices, paying close attention to edge cases and potential performance issues. By following these guidelines and best practices, you can create React applications that deliver optimal user experiences across a wide range of screen sizes and devices.

• How to re-render the React component when the browser is resized? | Learn how to use the useEffect hook and the window.addEventListener method to re-render a React component when the browser is resized.
• Re-render a React Component on Window Resize | Oct 20, 2020 ... Listen for Resize. React doesn't have a resize event baked into it, but we can listen to the native browser window resize event from within our ...
• How to Rerender the View on Browser Resize with React? | by John ... | Sometimes, we want to re-render the view on browser resize with React.
• Re-rendering React Components on Window Resizes With a ... | While building a mobile friendly React app, I found myself wanting to accomplish something out of the...
• How to Re-render Browser View on Window Resize in React 18 ... | This post will teach you how to re-render the component or browser view when the window is resized in React JS.
• Rerender animation on viewport change (react) - GSAP - GreenSock | Hi, I originally posted about spacing out images diagonally in gsap in a separate thread and was able to figure that out. However, I ran into an issue when I added in my entrance animation and am trying to see if there is a better approach. The images on the slider move from top right to bottom l...
• How to re-render on browser resize in React JS | Jul 15, 2022 ... How to re-render on browser resize in React JS · Create state variables for window width and height · Create a function that assigns window ...
• Resizing the window triggers more re-renders than needed · pmndrs ... | I've been playing around with the resize prop of Canvas, and I noticed that when I pass something like resize={{ debounce: 100 }}, which is equivalent to { debounce: { scroll 100, resize: 100 } }, ...
• AdvancedTexture just appears on rerender - Questions - Babylon.js | I already posted a question here: but I am afraid that this are two different problems I have and since I really want to come forward with my project and can’t figure out how to solve my rerender problem, I’d like to state the issue here again. As requested I opened a git repo: In README.md I describe the issue as problem 2. Basically it is that my Rectangle is just appearing on a rerender/resize of the browser and I can’t figure out why. I want that the rectangle appears after first ren...