The latest version of the popular jQuery library, jQuery 4.0.0, is here. It’s the first major update in nearly a decade and brings several important changes. The release focuses on improved security, performance, and modern browser compatibility. Developers can now download it from jquery.com and start using the new features right away.

Enhanced Security with Trusted Types Support

One of the biggest updates in jQuery 4.0.0 is support for Trusted Types. This feature helps websites stay secure by ensuring that only trusted HTML content is used when manipulating the page. It works with the TrustedHTML interface, making sure that jQuery methods follow browser security policies like Content Security Policy (CSP). This is especially important for preventing cross-site scripting (XSS) attacks.

In addition, jQuery has improved how it loads scripts via AJAX. While some requests already used tags to manage attributes like crossdomain, the library now switches most asynchronous script requests to use tags instead of inline scripts. This change helps avoid CSP errors and makes scripts load more securely. There are still some cases where XMLHttpRequest (XHR) is used, such as when passing specific options, but overall, the new approach enhances security and compatibility.

Streamlined Build and Modern JavaScript Features

Another major change is the removal of deferred objects and callbacks from the core build. Deferreds, which have long supported the Promises A+ standard, can still be used but are largely replaced by native JavaScript promises. These native promises work in most modern browsers, except IE 11, which means developers supporting older browsers will need to include polyfills or use the main build.

This update aims to modernize jQuery and make it easier for developers to write cleaner, more efficient code. Most promise-based workflows can now switch to native Promise methods, simplifying asynchronous programming. However, for those who need to support IE 11, sticking to the main build or adding a polyfill is recommended.

Other Important Changes and Compatibility

jQuery 4.0.0 also adjusts how certain events behave. For example, the focus event order now follows the latest W3C specifications. This means that the sequence of focus, blur, focusin, and focusout events aligns with current browser standards. This change is breaking, so developers should test their code accordingly.

Additionally, internal methods such as push, sort, and splice have been removed from the jQuery prototype. These were used internally and didn’t behave like typical jQuery methods. Developers using these methods directly will need to update their code to use standard JavaScript array methods instead.

With this release, jQuery continues its evolution, focusing on security, modern JavaScript features, and compliance with latest standards. The library now no longer supports IE 10 or older versions. Meanwhile, jQuery remains a backbone for many websites, supporting over 70% of all sites according to recent surveys. As part of the OpenJS Foundation, it aims to stay relevant and useful for years to come.

Overall, jQuery 4.0.0 brings significant improvements for developers, especially those working with security and modern browsers. It’s a step toward a more secure and efficient web development experience, even as it phases out support for older browsers.

Inspired by

• https://www.infoworld.com/article/4120307/jquery-4-0-0-javascript-library-features-trusted-types.html

Sources

• jquery.com
• jquery.com
• mozilla.org
• github.com
• w3techs.com