| jQuery 4.0.0 Close To Release |
| Written by Ian Elliot |
| Thursday, 04 September 2025 |
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The release candidate of jQuery 4.0 has been released, with a slim build option that excludes the ajax and effects modules as well as excluding Deferreds and Callbacks. jQuery can be considered as JavaScript's standard library and the workhorse of the front end is still the third most used web framework according to the 2025 Stack Overflow Survey. A fast, small, and feature-rich JavaScript library. it is designed to make things like HTML document traversal and manipulation, event handling and animation simpler with an easy-to-use API that works across most browsers. jQuery has long been about ironing out the differences between browsers and providing a powerful toolkit of functions that get the job done more simply. jQuery 4, which has been in beta since February 2024 and has now reached Release Candidate 1, will bring the framework up to date. According to Timmy Willison, Team Lead for jQuery Core, writing on the jQuery blog: Many of the breaking changes are ones the team has wanted to make for years, but couldn’t in a patch or minor release. We’ve trimmed legacy code, removed some previously-deprecated APIs, removed some internal-only parameters to public functions that were never documented, and dropped support for some “magic” behaviors that were overly complicated.
In this release, updated version of the slim build has removed more than previous versions. The thinking behind the slim build is that developers don't always need to use ajax, or might prefer to use a standalone library that focuses on ajax requests. Similarly, it can be simpler to use a combination of CSS and class manipulation for web animations. The dropping of Deferred and Callbacks is a response to the fact that all of jQuery’s supported browsers (except for IE11) now have support for native Promises across the board, so Deferreds and Callbacks are no longer needed in most cases. While the size of jQuery is very rarely a load performance concern, the slim build is about 8k gzipped bytes smaller than the regular version. There's better support for binary data in this release, including FormData, with jQuery.ajax now treating it as a known data type. In earlier versions, binary data was not a known data type and was converted to a string. Developers wanting to use binary data needed to disable data conversion and handle the data manually, but this is no longer necessary. Automatic JSONP promotion has been removed in this version. Until now, jQuery.ajax with dataType: "json" with a provided callback would be converted to a JSONP request. The new version has been changed to follow the preferred way to interact with a cross-domain backend using CORS, which works in all browsers that jQuery 4.0 supports. New in jQuery 4.0 is support for Trusted Types. This means that HTML wrapped in TrustedHTML can be used as input to jQuery manipulation methods in a way that doesn't violate the security policy directive. Other changes aimed at making JQuery more compliant is the changing of most asynchronous script requests to use <script> tags. This avoids any CSP errors caused by using inline scripts. The team says there are still a few cases where XHR is used for asynchronous script requests, such as when the "headers" option is passed, but they now use a <script> tag whenever possible. Under the covers, the jQuery source has been migrated from AMD to ES modules. The jQuery source has always been published with jQuery releases on npm and GitHub, but could not be imported directly as modules without RequireJS, which was jQuery's build tool of choice. The developers have since switched to Rollup for packaging jQuery and run all tests on the ES modules separately. JQuery 4.0.0-rc.1 release candidate is available now. A 4.0 upgrade guide and jQuery Migrate release are also available, but both are subject to changes before the final jQuery 4.0.0 release.
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| Last Updated ( Thursday, 04 September 2025 ) |
