JavaScript-based front-end performance optimization experience sharing

With the development of the Internet, front-end development has become an important part of the entire web application. Front-end performance optimization is an eternal topic, which can improve the website access speed and user experience to a certain extent. This article will combine my own experience to share front-end performance optimization experience based on JavaScript.

1. Minimize the number of HTTP requests
   HTTP requests are an aspect that needs attention in front-end performance optimization. Because each request requires communication with the server, this will consume a certain amount of time. Therefore, reducing the number of HTTP requests can improve the loading speed of your website. We need to merge resources as much as possible, such as merging CSS and JavaScript files, and reducing image requests through CSS Sprites technology.
2. Use browser caching mechanism
   Browser caching is an effective way to reduce HTTP request time. Since the browser will cache the requested file locally, it can be read directly from the local during the next request, which can save server request time and improve request efficiency.
3. Compress JavaScript and CSS files
   JavaScript and CSS files may contain a lot of spaces and comments. Although these contents are helpful for code readability, they will also increase the file size and increase HTTP requests. time. Therefore, we can remove these useless content and use compression tools to compress the code and reduce request time.
4. Lazy loading of JavaScript and CSS files
   Some JavaScript and CSS files may not be necessary for page loading. We can consider delaying loading of these files until they are needed. This can improve the rendering speed of the page and shorten the loading time of the page.
5. Lazy loading of images
   Some pages may have many images. If you load all the images at once, it will increase the loading time of the page. Lazy loading technology allows images to be loaded only when they are needed on the page, thus avoiding the problem of loading all images at once.
6. Reduce the number of DOM operations
   DOM operations are a time-consuming part of the front-end. Therefore, we should try to reduce the number of DOM operations when writing code. Multiple DOM operations can be combined together to reduce the number of queries for DOM objects.
7. Use event delegation
   Event delegation can reduce the number of event registrations, thereby reducing browser resource usage. The specific method is to bind the event to the parent node, and then execute the relevant logic through the event delegation mechanism after the child node triggers the event.

Summary
Front-end performance optimization is very important because it is directly related to the user experience. We need to optimize front-end performance based on specific scenarios. During the optimization process, we need to pay attention to reducing the number of HTTP requests as much as possible, using the browser caching mechanism, compressing JavaScript and CSS files, delaying loading of JavaScript and CSS files, lazily loading images, and reducing DOM. The number of operations and optimization techniques such as using event delegation. Mastering these skills can improve website access speed and user experience.

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