How to modify lazy loading JavaScript

Lazy loading (defer) JavaScript is a method of optimizing website performance. Only the necessary HTML and CSS are loaded when the page is loaded, while JavaScript is loaded lazily. This speeds up page loading and improves user experience.

However, in some cases, lazy loading may cause JavaScript code to fail to execute, thus affecting the functionality of the website. At this time, we need to modify the lazy loading JavaScript. Here are some common methods:

1. Move lazy loading JavaScript to the bottom of the page

Lazy loading JavaScript is usually placed at the head of the page, before the DOM is loaded. Just load. This may cause JavaScript code execution to fail because the DOM object has not been fully loaded. The solution is to move the lazy loading JavaScript to the bottom of the page and ensure that the DOM is loaded before loading the JavaScript.

2. Using asynchronous loading

In addition to lazy loading (defer), we can also use asynchronous loading (async). Asynchronous loading is similar to defer, but the order is not guaranteed. When a JavaScript file is marked as loaded asynchronously, the browser will continue to parse the page while the file is loaded, without waiting for the file to download and execute. This improves page loading speed and does not affect the functionality of the website.

3. Separate JavaScript files

Sometimes, the page needs to load many JavaScript files, which may affect the page loading speed. To improve the situation, we can combine multiple JavaScript files into a single file and place it at the bottom of the page. This reduces the number of HTTP requests and speeds up page loading.

4. Compress JavaScript files

JavaScript files are usually large and can be compressed into smaller files using compression tools. Compressed files can reduce file size, speed up downloads, and improve page loading times.

5. Loading JavaScript using a CDN

CDN (Content Delivery Network) is a method of accelerating a website by deploying servers around the world to increase access speeds. Using a CDN to load JavaScript files improves download speeds and reduces load on the server.

To summarize, lazy loading of JavaScript is a way to optimize website performance, but sometimes modifications need to be made to ensure it operates properly. The above methods can help you modify your lazy-loaded JavaScript and make your page load faster.

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