optimizing performance for better metrics in lighthouse React App-CodePudding

hello everyone I am working on a big react app and my new task is about optimizing it's performance to get a better performance score in lighthouse the big issue that i have is about lcp(largest contentfull paint) the element that now is known as our page lcp is a div that has an image background , i've read many articles about how to optimize that image but all of talk about static assets that can't be my option , my app uses dynamic rendering for elements and also all images are dynamic , never mind , the issue that i just want to solve is how to preload that background image while my script still don't parse it , if i want to make it clear i want to preload a url with webpack when the element that render that image isn't painted on screen , doe's webpack support something like this ? i've read previousely something about dynamic import for the main bundle of react app

i need webpack to start fething my url and cache the response (as its default behavior) and when i need the url it instanly load and be painted on the screen

CodePudding user response：

Well, if you are using react purely client-side, then you can give a shot to link rel preconnect. It will pre-connect to given domain, and should improve performance. You might also google search for link rel prefetch and link rel preload.

While using react client side, other options is you using prefetching using somthing like react-query if the image link is coming as a result of API response from server (JSON, etc.)

CodePudding user response：

It's possible to use Webpack to preload dynamic images in your React app. One way to do this is to use the link element with the rel="preload" attribute to preload the image before it is rendered on the page.

Here is an example of how you could use this approach to preload a dynamic image in your React app:

import React from 'react';

function MyComponent() {
  const imageUrl = getDynamicImageUrl();

  return (
    <div>
      {/* Preload the image with the link element */}
      <link rel="preload" href={imageUrl} as="image" />
      {/* Render the image */}
      <img src={imageUrl} alt="My image" />
    </div>
  );
}

export default MyComponent;

In this example, the link element is used to preload the image with the rel="preload" attribute. The href attribute specifies the URL of the image to preload, and the as attribute specifies the type of asset being preloaded (in this case, an image).

When the component is rendered, the link element will cause the browser to start loading the image in the background, even if the img element has not yet been rendered on the page. This can help improve the performance of your app