Meta Description: jQuery 4.0.0 is officially here after nearly a decade. Learn about the breaking changes, modern browser support, ES modules, Trusted Types, and how to upgrade from jQuery 3.x.
After almost a decade since its last major version, the jQuery team has officially released jQuery 4.0.0 on January 17, 2026, coinciding perfectly with the library's 20th anniversary. This landmark release represents a significant shift from legacy compatibility to modern web standards while maintaining the stability that millions of websites depend on.
The Journey: From 2006 to 2026
Twenty years ago, John Resig introduced jQuery at BarCamp in New York City on January 14, 2006. What started as a solution to browser inconsistencies has become one of the most influential JavaScript libraries in web development history, currently powering an estimated 90% of all websites.
jQuery 4.0.0 marks the first major version release in nearly 10 years, bringing long-awaited modernizations, breaking changes, and performance improvements that the team has wanted to implement for years.
What's New in jQuery 4.0.0?
1. Dropping Legacy Browser Support
The most significant change is the removal of support for Internet Explorer 10 and older versions. While this might seem overdue to some developers, the jQuery team has taken a measured approach.
Supported Browsers:
- Internet Explorer 11 (temporary, will be removed in jQuery 5.0)
- Chrome, Edge, Firefox, Safari (current and previous versions)
- iOS Safari (current through current minus two versions)
- Android (current and previous versions)
No Longer Supported:
- Internet Explorer 10 and earlier
- Edge Legacy (pre-Chromium)
- Firefox versions older than the last two releases (excluding ESR)
- iOS versions earlier than the last three releases
- Android Browser
If your project still requires these older browsers, the recommendation is to stick with jQuery 3.x, which will continue to receive security updates.
2. Migration to ES Modules
The jQuery source code has been migrated from AMD to ES modules, marking a special milestone in the library's evolution. This change brings several benefits:
- Direct compatibility with modern build tools like Webpack, Rollup, and Vite
- Better tree-shaking capabilities for reduced bundle sizes
- Support for native browser module loading via
<script type="module"> - Improved integration with server-side rendering frameworks
The primary jQuery distribution remains a UMD module that works in both AMD and non-AMD environments, ensuring backward compatibility for most use cases.
3. Trusted Types Support for Enhanced Security
jQuery 4.0 adds support for Trusted Types, allowing HTML wrapped in TrustedHTML objects to be used safely with jQuery manipulation methods under strict Content Security Policy configurations. This enhancement significantly improves security for applications with stringent CSP requirements.
Additionally, most asynchronous script requests now use <script> tags instead of inline scripts to avoid CSP violations.
4. Removal of Deprecated APIs
Many utility methods that browsers now implement natively have been removed, including:
-
jQuery.isArray()→ UseArray.isArray() -
jQuery.parseJSON()→ UseJSON.parse() -
jQuery.trim()→ UseString.prototype.trim() -
jQuery.now()→ UseDate.now() - Various CSS-related internals replaced by native browser APIs
These removals help reduce the library's file size and encourage developers to use modern JavaScript features.
5. Slim Build Option
For developers who don't need everything jQuery offers, a "slim" build is available that excludes:
- AJAX functionality
- Effects/animations
- Deprecated APIs
The slim build is approximately 8KB smaller (gzipped) than the regular version, making it ideal for projects that handle AJAX with fetch API or use CSS for animations.
6. Updated Event Handling
jQuery 4.0 aligns focus-related events with the current W3C specification, no longer overriding native browser behavior. This ensures event sequences follow standardized orders used by modern browsers.
Should You Upgrade?
When to Upgrade:
- Your application no longer needs to support IE 10 or older browsers
- You want to take advantage of modern JavaScript features
- You're using modern build tools and want better integration
- You need enhanced Content Security Policy support
When to Wait:
- Your project still supports legacy browsers
- You rely on deprecated APIs that have been removed
- You have a large codebase that hasn't been tested with jQuery 4.0
How to Upgrade
The jQuery team has prepared comprehensive resources to help with the transition:
- Upgrade Guide: A detailed guide covering all breaking changes
- jQuery Migrate Plugin: Helps identify and fix compatibility issues
- Testing: Thoroughly test your application with jQuery 4.0 before deploying
Installation Options:
Via CDN:
<script src="https://code.jquery.com/jquery-4.0.0.min.js"></script>
Via npm:
npm install jquery@4.0.0
Slim Build:
<script src="https://code.jquery.com/jquery-4.0.0.slim.min.js"></script>
The Bigger Picture: jQuery's Role in Modern Web Development
While frameworks like React, Vue, and Angular dominate new project development, jQuery remains critical infrastructure for millions of existing websites, WordPress themes, and enterprise applications. This release demonstrates that jQuery isn't trying to compete with modern frameworks but rather serve its existing ecosystem while embracing modern standards.
The library's mission of cross-browser compatibility has been largely accomplished—modern browsers now implement consistent APIs following W3C specifications. jQuery 4.0 acknowledges this reality by shedding unnecessary legacy code while maintaining stability for the vast web ecosystem that depends on it.
What's Next?
jQuery 5.0 will likely remove IE 11 support entirely, but given that jQuery 4.0 took nearly a decade to release, significant version updates will remain infrequent. The team prioritizes stability and backward compatibility over rapid iteration, which is exactly what the library's users need.
Conclusion
jQuery 4.0.0 represents a carefully balanced modernization of one of the web's most important libraries. It drops outdated browser support, embraces modern JavaScript standards, improves security, and reduces file size—all while maintaining the stability that millions of websites depend on.
For teams maintaining jQuery-based applications, this release offers a clear migration path to modern web development practices without requiring a complete rewrite. For new projects, it serves as a reminder that sometimes the most reliable tool is the one that's been battle-tested for two decades.
Whether you upgrade immediately or continue with jQuery 3.x, this release marks an important milestone in web development history and sets the foundation for jQuery's next chapter.
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