jQuery
By OpenJS Foundation
jQuery is a fast, lightweight JavaScript library that simplifies HTML DOM manipulation, event handling, animation, and AJAX requests through a concise, cross-browser API.
Definition
jQuery is a fast, lightweight JavaScript library that simplifies HTML DOM manipulation, event handling, animation, and AJAX requests through a concise, cross-browser API.
Overview
Released in 2006 by John Resig, jQuery solved a real problem of its era: browsers implemented the DOM and event models inconsistently, so simple tasks like selecting elements or making an AJAX call required verbose, browser-specific code. jQuery wrapped this complexity in a single, chainable `$()` function, letting developers write `$('.button').on('click', fn)` instead of dozens of lines of cross-browser boilerplate. At its peak in the early-to-mid 2010s, jQuery was used on the majority of websites, and it remains one of the most widely deployed JavaScript libraries in history, still present in a huge share of legacy and CMS-driven sites (including many built on WordPress). Its plugin ecosystem made it easy to add sliders, modals, form validation, and animations without writing raw DOM code. Modern browsers have since standardized most of what jQuery abstracted away — `querySelector`, `fetch`, and CSS transitions cover much of its original value — and component-driven frameworks like React and Vue.js have replaced direct DOM manipulation with declarative rendering for new applications. As a result, jQuery is rarely chosen for greenfield projects today, but understanding it remains useful for maintaining legacy codebases and older enterprise systems.
Key Features
- Concise `$()` selector syntax for querying and manipulating the DOM
- Chainable method calls for combining multiple operations in one statement
- Cross-browser normalization of DOM and event-handling quirks
- Built-in AJAX helpers for asynchronous HTTP requests
- Animation and effects API (fade, slide, custom animations)
- Large plugin ecosystem for UI widgets and form utilities
- Minimal file size relative to the functionality it provides
- Extensive documentation and decades of community Q&A