What is jQuery?

Last reviewed May 28, 2026 Content v20260528

Track mode

client_jquery

Means

In-browser jQuery

Reading

~1 min

Level

beginner

This lesson

This lesson teaches What is jQuery?: the concepts, APIs, and habits you need before advancing in jQuery.

Without What is jQuery?, you will struggle to read or extend jQuery codebases and playground exercises.

You will apply What is jQuery? in contexts like: WordPress themes, admin panels, older SPAs, and pages awaiting incremental modernization.

Write JavaScript, click Run—jQuery 3.7 loads from CDN; use mountApp(function($) { ... }) on #playground-root when the DOM is ready; printOutput feeds the terminal.

After solid JavaScript—and ideally TypeScript—before starting the jquery track.

jQuery (circa 2006–2015 golden era) standardized painful cross-browser DOM code. Version 3.x is leaner and drops old IE hacks, but the mental model persists in millions of pages.

Core pieces

$ / jQuery — factory function returning collections
Chaining — most methods return the same collection
Plugins — extend $.fn for reusable widgets
Ajax helpers — shorthand around XMLHttpRequest

Not a SPA framework

Unlike Vue or React, jQuery does not own component state or a virtual DOM—you orchestrate updates imperatively.

Interview

Q: Library or framework?
A: A focused DOM/Ajax library; apps layer their own architecture on top.
Q: Still relevant?
A: For maintenance and gradual migration—not for greenfield architecture decisions.

Interview prep

What is jQuery in one sentence?: A DOM and Ajax helper library centered on chainable collections—not a component framework like Vue or React.

Playground

Runs in your browser in a sandboxed frame. Backend runners appear when this track’s profile allows them.

Discussion

Past discussion is visible to everyone. Only logged-in users can post comments and replies.

Starter discussion topics

Library vs framework?
Core problem it solved?

No discussion yet. Be the first to ask a question.