jQuery 4.0 Unveiled: New Features, Modern Architecture, and Upgrade Guide

On February 24, 2026, marking jQuery’s 20th anniversary, the library launched version 4.0 – its first significant release in ten years.

The update focuses on three core goals: simplification, modernization, and efficiency. The development team removed legacy code, deprecated APIs, and discontinued support for several outdated browsers.

Most existing projects require only minimal code changes to upgrade. The official upgrade guide and the jquery-migrate plugin help lower migration costs.

Browser compatibility changes include dropping support for Internet Explorer 10 and earlier, the legacy Edge engine, and older iOS/Android browsers. Internet Explorer 11 remains supported for now but will be removed in the upcoming 5.0 release.

Architecturally, jQuery’s source moved from AMD modules to native ES modules, allowing developers to import it with <script type="module"> and use modern bundlers such as Rollup, Vite, or Webpack instead of RequireJS.

Security enhancements add Trusted Types support, ensuring that HTML wrapped in TrustedHTML can be safely used with jQuery’s DOM methods, and most asynchronous script requests have been replaced by static <script> tags to avoid CSP violations.

To achieve a smaller footprint, jQuery 4.0 removed several functions that are now natively available: jQuery.isArray, jQuery.parseJSON, jQuery.trim, and jQuery.now. Their native equivalents – Array.isArray(), JSON.parse(), String.prototype.trim(), and Date.now() – reduce the gzipped size by over 3 KB.

Further size reductions come from eliminating the Deferreds and Callbacks modules, bringing the gzipped bundle down to roughly 19.5 KB, a new lightweight milestone.

The community has praised the trimming effort; Reddit users note that nearly half of the changelog consists of removals, while Hacker News commenters highlight jQuery’s low mental‑cost, stability, and predictability.

Despite modern frameworks, jQuery remains valuable for maintaining large legacy codebases, offering quick, low‑overhead DOM manipulation, cross‑browser consistency, a rich plugin ecosystem, readability for non‑experts, progressive enhancement, server‑side rendering compatibility, and simple dependency management.

Developers can obtain jQuery 4.0 via CDN or npm. Installation is as simple as: npm install [email protected] jQuery 4.0 continues the “Write Less, Do More” philosophy, demonstrating that a classic tool can evolve to meet modern development demands while retaining its unique strengths.

Author: 洛逸 References: https://jquery.com/upgrade-guide/4.0/ https://github.com/jquery/jquery-migrate