jQuery 4.0 Arrives: After a Decade, the Frontend Veteran Bids Farewell to IE

On January 17, 2026, the jQuery team released jQuery 4.0.0, the first major version in twenty years, positioning it as a clean‑up that removes historical baggage and aligns the library with modern web standards.

The most visible change is the abandonment of support for Internet Explorer 10 and earlier; IE 11 remains supported for now but will be removed in the planned jQuery 5.0. Older Edge (non‑Chromium), iOS 11‑ and earlier, and Firefox 65‑ and earlier are also dropped, allowing the library to delete many compatibility hacks and reduce the gzipped bundle by roughly 3 KB.

The source code has been fully migrated from AMD/RequireJS to native ES Modules and is now bundled with Rollup. This enables direct use of <script type="module"> and better integration with modern bundlers such as Vite and Webpack.

jQuery 4.0 adds support for Trusted Types. When developers call methods like .html(), the library now ensures the HTML string passes a trusted‑type policy, satisfying the CSP directive require-trusted-types-for and improving security for enterprise applications.

A “slim” build removes deprecated APIs such as jQuery.isArray, jQuery.trim, jQuery.parseJSON, and array methods like push, sort, splice from the jQuery prototype. It also drops the Deferreds and Callbacks modules (the slim bundle is roughly 20 KB gzipped). Developers are encouraged to use native Array.isArray(), String.prototype.trim(), JSON.parse(), and native Promise instead.

The Hacker News discussion framed the release as a debate between “complexity vs. pragmatism”. Some view jQuery as a scapegoat for spaghetti code, while others argue that its concise API (e.g., $('.el').hide()) still offers lower cognitive load than equivalent vanilla code and that large WordPress and legacy codebases keep it relevant.

A third perspective notes the rise of HTMX and similar libraries, suggesting a return to server‑rendered HTML with lightweight client interaction. In this context, the slimmer jQuery 4.0 or alternatives like Alpine.js can occupy a niche without competing directly with React or Vue.

The release is not intended to challenge modern frameworks but to provide a stable, unified, and elegant DOM manipulation API after shedding polyfills that native JavaScript now handles.