jQuery 4.0.0 Released: Major Updates after 10 Years

John Resig introduced jQuery 20 years ago. Now, looking forward, version 4.0.0 brings significant modernizations. While there are breaking changes, the team expects most users to upgrade with minimal effort.

IE < 11 Support Removed

jQuery 4.0 drops support for IE 10 and older. Support for IE 11 remains for now but is planned to be removed in jQuery 5.0. They have also dropped support for Edge Legacy, older iOS and Firefox versions. If you need to support these very old browsers, you should stick with jQuery 3.x.

Modernization & ES Modules

The jQuery source has finally migrated from AMD to ES modules! This allows for better compatibility with modern build tools like Rollup and webpack. You can now use <script type="module"> more effectively.

Trusted Types & CSP

Security is a big focus. jQuery 4.0 adds support for Trusted Types. It ensures that HTML wrapped in TrustedHTML can be used in manipulation methods without violating CSP directives. Most asynchronous script requests have also been switched to use <script> tags to avoid CSP errors.

Deprecated APIs Removed

Several functions that have been deprecated for years are now gone. These include:

• jQuery.isArray (Use Array.isArray())
• jQuery.parseJSON (Use JSON.parse())
• jQuery.trim (Use String.prototype.trim())
• jQuery.isFunction
• jQuery.isNumeric

The removal of these legacy APIs, combined with dropping old IE support, reduced the gzipped size by over 3KB!

Slim Build Updates

The slim build is now even smaller (~19.5k bytes gzipped) by removing Deferreds and Callbacks. Since native Promises are supported in all target browsers (except IE11), you likely don't need jQuery's custom implementation anymore.

How to Upgrade

You can grab the new release from the jQuery CDN or npm:

npm install [email protected]