In the previous article, Why we needed Javascript, we saw how browsers gained the ability to run code, transforming static web pages into interactive experiences.

That solved one of the web's biggest limitations, but it also exposed a new problem.

As developers started building richer websites, they discovered that the same Javascript code often behaved differently across browsers. Writing Javascript had become possible. Writing Javascript that worked everywhere was another challenge entirely.

The problem: browsers didn't agree

The late 1990s and early 2000s were an exciting time for the web. Javascript was becoming more popular, websites were growing increasingly interactive, and browsers were competing aggressively for users.

Unfortunately, they weren't always competing in the same direction.

There wasn't yet a fully consistent standard for how browsers should behave. Internet Explorer, Netscape Navigator, Opera, Safari, and later Firefox often introduced their own APIs, features, and quirks.

As a result, developers frequently discovered that code working perfectly in one browser would fail in another.

For example, attaching a click event wasn't always done the same way.

// Internet Explorer
element.attachEvent("onclick", handler);
// Most other browsers
element.addEventListener("click", handler);

Even selecting elements, handling events, or reading CSS properties could require different code depending on the browser.

Supporting all of those browsers quickly became exhausting. Projects filled with browser-specific conditions, compatibility fixes, and workarounds, leaving developers spending as much time fighting browser inconsistencies as building new features.

The larger an application became, the harder those differences were to maintain.

Developers needed a better solution.

jQuery arrives

In 2006, John Resig introduced jQuery with a simple goal:

Write less, do more.

Instead of forcing developers to remember dozens of browser differences, jQuery provided a simple, consistent API that worked across all major browsers, making cross-browser development dramatically easier.

It didn't replace Javascript. Instead, it provided a simpler and more consistent way to work with it.

Conceptually, jQuery sat between your code and the browser, hiding many of the differences between browser implementations.

                Your code
                    ↓
                 jQuery
              /     |     \
             IE  Firefox Safari

Much of that convenience came from simplifying DOM manipulation, event handling, animations, and AJAX into a small, consistent set of functions.

Let's look at what that meant in practice.

One of the biggest reasons developers embraced jQuery was how much simpler common tasks became.

Before jQuery

Selecting an element:

document.getElementById("menu");

Adding a click event:

document.getElementById("button").addEventListener("click", function () {
    alert("Clicked!");
});

After jQuery

Selecting an element:

$("#menu");

Adding a click event:

$("#button").click(function () {
  alert("Clicked!");
});

The difference looks small in these examples, but across hundreds or thousands of lines of code, the productivity gains quickly added up.

The shorter syntax made code easier to read, but jQuery's biggest advantage wasn't saving a few keystrokes.

By hiding browser-specific differences behind a consistent API, developers could write code once and spend far less time debugging compatibility issues.

Plugins changed everything

As jQuery grew in popularity, it became much more than a compatibility library.

Need form validation? There was a plugin.

Need a date picker? There was a plugin.

Need a carousel, lightbox, drag-and-drop interface, or animation? There was a plugin.

An enormous ecosystem grew around jQuery, allowing developers to add sophisticated functionality with only a few lines of code instead of building everything from scratch.

Combined with excellent documentation and a vibrant community, jQuery quickly became one of the most influential libraries in the history of web development.

At its peak, it powered the vast majority of websites on the internet, making it almost impossible to build for the web without encountering jQuery.

The beginning of the end

Ironically, jQuery became so successful that browsers eventually adopted many of the APIs and patterns developers had come to rely on.

Modern browsers became far more consistent, while Javascript and the browser platform continued to evolve.

Many of the conveniences that once made jQuery essential became part of the web itself. Features such as querySelector(), fetch(), classList, and improved event handling allowed developers to write simpler, cross-browser code without relying on a library.

At the same time, frameworks such as React, Angular, and Vue emerged, solving problems that jQuery had never been designed to address, such as building and managing large, interactive applications.

Today, jQuery remains an important part of web history. It solved a real problem at exactly the right time and helped shape the modern web, even if many of its original responsibilities are now handled directly by browsers and modern Javascript.

Key takeaways

  • jQuery solved one of the biggest challenges of early web development by providing a consistent API across browsers, allowing developers to write less compatibility code.
  • Its plugin ecosystem and simple syntax dramatically accelerated development, making jQuery one of the most influential libraries in web history.
  • As browsers standardized and Javascript evolved, many of jQuery's core features became built into the web platform, paving the way for modern frameworks to solve a new generation of problems.

Frequently asked questions

Was jQuery a programming language?

No. jQuery is a Javascript library, not a programming language. It provides a collection of functions that make common Javascript tasks easier and more consistent across different browsers.

Is jQuery still used?

Yes. Although many new projects no longer depend on it, jQuery is still used by millions of websites, especially older applications and content management systems like WordPress. It also continues to be actively maintained.

Should you learn jQuery today?

If you're learning web development, focus on modern Javascript first. Today's browsers support many features that once required jQuery, and modern frameworks often don't rely on it. However, understanding jQuery is still valuable if you maintain legacy applications, work with existing codebases, or develop for platforms that still use it.

Does WordPress still use jQuery?

Yes. WordPress still includes jQuery, and many themes and plugins rely on it for interactive features such as sliders, menus, form validation, and pop-ups.

That said, modern WordPress development is gradually moving away from jQuery. The Block Editor (Gutenberg) is built with React, and many new themes and plugins now prefer modern Javascript APIs instead of depending on jQuery.

If you're maintaining an existing WordPress site, you'll almost certainly encounter jQuery. However, if you're building new functionality today, modern Javascript is generally the recommended approach.

Explore the series

Every technology exists because it solved a problem.

The "Why We Needed..." series looks back at the challenges developers faced, the solutions they created, and how each innovation paved the way for the next.

  • Why We Needed Javascript
  • Why We Needed jQuery (You're reading this)
  • Why We Needed Single-Page Applications (coming soon)
  • Why We Needed React (coming soon)
  • Why We Needed Node.js (coming soon)