The jQuery Era (2008–2015): When One Library United the Web
In 2008, writing JavaScript meant writing it four times. Once for Firefox 2, once for IE6, once for IE7, and once that you hoped might work in Safari. Every browser had different DOM APIs, different event models, different AJAX implementations. XMLHttpRequest was a Microsoft-invented API that other browsers had copied imperfectly. Attaching a click handler looked different in every browser.
jQuery solved this with a single promise: Write Less, Do More. One selector syntax. One event API. One AJAX wrapper. One animation system. Cross-browser, every time, in one 32KB file.
By 2010 it was on 40% of all websites. By 2013, over 90% of all sites that used a JavaScript library used jQuery.
Then React appeared, and everything changed again.
What the world looked like before jQuery
To appreciate why jQuery spread so fast, you need to feel the pain it erased.
Attaching a click handler in 2007:
// The "clean" cross-browser way, circa 2007
function addEvent(element, eventName, fn) {
if (element.addEventListener) {
element.addEventListener(eventName, fn, false); // W3C
} else if (element.attachEvent) {
element.attachEvent('on' + eventName, fn); // IE
} else {
element['on' + eventName] = fn; // Fallback
}
}
// Using it
var button = document.getElementById('submit-btn');
addEvent(button, 'click', function() {
// Now in IE, 'this' might be wrong here. Fun.
alert('Clicked');
});
Making an AJAX call in 2007:
function makeRequest(url, callback) {
var xhr;
if (window.XMLHttpRequest) {
xhr = new XMLHttpRequest(); // Firefox, Safari
} else if (window.ActiveXObject) {
try {
xhr = new ActiveXObject("Msxml2.XMLHTTP"); // IE 6+
} catch (e) {
try {
xhr = new ActiveXObject("Microsoft.XMLHTTP"); // IE 5
} catch (e) {}
}
}
if (!xhr) return;
xhr.onreadystatechange = function() {
if (xhr.readyState === 4 && xhr.status === 200) {
callback(xhr.responseText);
}
};
xhr.open('GET', url, true);
xhr.send(null);
}
Every project carried this boilerplate or something similar. It was copied from Stack Overflow, from blogs, from colleagues. It worked, mostly. Then you'd find an IE edge case and the whole thing would fall apart.
What jQuery looked like
The same operations with jQuery 1.4:
// Click handler
$('#submit-btn').click(function() {
alert('Clicked');
});
// Or the modern way, even in 2010:
$('#submit-btn').on('click', function() {
alert('Clicked');
});
// AJAX call
$.ajax({
url: '/api/data',
type: 'GET',
success: function(data) {
// data is already parsed if JSON
console.log(data);
},
error: function(xhr, status, error) {
console.error(error);
}
});
// Or the shorthand
$.getJSON('/api/data', function(data) {
console.log(data);
});
For developers who had spent years on the boilerplate, this felt like magic. Same code, every browser, every time.
The things jQuery made easy that were genuinely hard
DOM manipulation
Before jQuery, moving elements around the DOM was tedious. Creating elements, setting attributes, inserting them — each step was verbose and error-prone.
// Old way: create a list item and append it
var li = document.createElement('li');
li.setAttribute('class', 'item');
li.appendChild(document.createTextNode('New item'));
document.getElementById('my-list').appendChild(li);
// jQuery way
$('#my-list').append('<li class="item">New item</li>');
The ability to pass HTML strings to jQuery methods and have them parsed was genuinely transformative. Templates became trivial. Dynamic lists became trivial.
Animations
CSS transitions didn't exist in browsers until 2009-2011, and support was incomplete through 2013. jQuery provided animate(), fadeIn(), fadeOut(), slideUp(), slideDown() — a complete animation library with cross-browser support.
// Animate any CSS property
$('#panel').animate({
opacity: 0.5,
height: '200px',
paddingTop: '20px'
}, 400, function() {
// Callback when animation completes
console.log('done');
});
// Built-in effects
$('#notification').fadeIn(200).delay(3000).fadeOut(400);
This powered an entire era of UI patterns: accordion menus, tabbed interfaces, modal dialogs, smooth page transitions. If you used a website between 2009 and 2014, you experienced jQuery animations constantly, whether you knew it or not.
Selectors and chaining
The CSS selector API (document.querySelector) didn't have cross-browser support until IE8, and querySelectorAll wasn't universal until IE9. jQuery's selector engine (Sizzle) gave you CSS selectors in every browser years before the native API was usable.
// Select complex nested elements
$('.user-list li:not(.inactive) a.email')
.addClass('verified')
.attr('data-verified', 'true')
.closest('li')
.addClass('verified-item');
The chaining model — every jQuery operation returns the jQuery object, so you can chain method calls — made complex DOM transformations readable in a single expression.
How we actually built applications
Real jQuery application code from around 2010-2012 looked like this:
// A "module" pattern, as we understood it then
var UserPanel = (function($) {
var $panel, $list, $form;
function init() {
$panel = $('#user-panel');
$list = $panel.find('.user-list');
$form = $panel.find('form.add-user');
bindEvents();
loadUsers();
}
function bindEvents() {
$form.on('submit', handleFormSubmit);
$list.on('click', '.delete-btn', handleDelete);
$list.on('click', '.edit-btn', handleEdit);
}
function loadUsers() {
$.getJSON('/api/users', function(users) {
renderList(users);
});
}
function renderList(users) {
$list.empty();
$.each(users, function(i, user) {
$list.append(renderUser(user));
});
}
function renderUser(user) {
return $('<li/>')
.attr('data-id', user.id)
.html(
'<span class="name">' + escapeHtml(user.name) + '</span>' +
'<button class="edit-btn">Edit</button>' +
'<button class="delete-btn">Delete</button>'
);
}
function handleFormSubmit(e) {
e.preventDefault();
var data = {
name: $form.find('[name=name]').val(),
email: $form.find('[name=email]').val()
};
$.ajax({
url: '/api/users',
type: 'POST',
contentType: 'application/json',
data: JSON.stringify(data),
success: function(user) {
$list.append(renderUser(user));
$form[0].reset();
}
});
}
function handleDelete(e) {
var $item = $(this).closest('li');
var userId = $item.data('id');
if (!confirm('Delete this user?')) return;
$.ajax({
url: '/api/users/' + userId,
type: 'DELETE',
success: function() {
$item.fadeOut(200, function() {
$(this).remove();
});
}
});
}
return { init: init };
})(jQuery);
$(document).ready(function() {
UserPanel.init();
});
This was sophisticated code by the standards of 2010. The module pattern, event delegation, separating concerns. It was also completely stateless — every update to the DOM was surgical, every state change had to be manually synchronized between the server and the DOM. There was no single source of truth. State lived in the DOM, in JavaScript variables, and on the server simultaneously, never quite in sync.
This is what React solved. Not the cross-browser issues jQuery had already fixed. The state synchronization problem.
The plugins ecosystem
jQuery's plugin architecture was where it truly became a platform. By 2012 there were thousands of plugins for every conceivable UI pattern:
- jQuery UI — draggable, droppable, resizable, sortable, autocomplete, datepicker, dialog, progressbar
- jQuery Validate — form validation with built-in rules and custom validators
- DataTables — fully-featured table plugin with sorting, pagination, server-side rendering
- Select2 — enhanced select boxes with search, tags, and remote data
- jQuery File Upload — multi-file upload with progress bars and drag-and-drop
- Fancybox / Colorbox — lightbox image galleries
- Slick / Owl Carousel — responsive carousels
- Chosen — another select enhancement (yes, there were multiple)
- Moment.js — date parsing and formatting (not jQuery but commonly used alongside it)
A fully-featured business application could be built almost entirely from jQuery plugins. Every enterprise CRM, every admin panel, every intranet from 2009-2015 was jQuery + jQuery UI + DataTables + some form validation plugin.
Where it started breaking
By 2012-2013, the patterns that worked for mostly-static pages started showing cracks as more and more UI logic moved client-side.
State synchronization hell. A page with a shopping cart, real-time inventory, user-specific pricing, and a live order total required updating dozens of DOM elements whenever anything changed. jQuery gave you the tools to do the updates. It gave you no help with when to do them or what the source of truth was.
String concatenation XSS. The pattern of building HTML strings in JavaScript and passing them to $().html() was an XSS vector. Every place you did '<span>' + userData + '</span>' you had a potential injection point. The ecosystem eventually added escapeHtml utilities but it was never baked into jQuery itself. The number of jQuery-era applications with stored XSS vulnerabilities from unescaped user data is enormous.
Callback nesting. Complex asynchronous flows — load user, then load their orders, then load product details for each order — created deeply nested callback chains. jQuery 1.5 introduced Deferred objects (a Promise-like API), which helped, but it wasn't widely adopted before Promises became standard.
// Classic "callback hell" circa 2012
$.getJSON('/api/user/123', function(user) {
$.getJSON('/api/orders?userId=' + user.id, function(orders) {
$.getJSON('/api/products?ids=' + orders.map(o => o.productId).join(','), function(products) {
$.getJSON('/api/recommendations?userId=' + user.id, function(recs) {
// By now you've forgotten what user was
render(user, orders, products, recs);
});
});
});
});
Performance on complex interactions. jQuery abstractions had overhead. Fine for a hundred DOM nodes. Noticeable when you were manipulating hundreds or thousands of elements on every user interaction.
The transition: 2013-2016
React was released in 2013 and Angular 1 was already gaining traction. But the transition wasn't immediate. Most production applications in 2013-2015 were still jQuery. jQuery was still the dependency that shipped on more websites than any other library.
The shift happened in a specific segment first: single-page applications. If you were building an app with complex, dynamic UI — a Gmail-like interface, a real-time dashboard, a collaborative tool — React or Angular made the state management tractable in a way jQuery never could.
For everything else — websites that mostly served content, forms that submitted to a server, admin panels that loaded pages — jQuery kept working fine. It still works fine. There are hundreds of millions of jQuery applications running today. The library is still maintained (3.7.x at time of writing). It will be running in 2035.
The narrative of "jQuery is dead" is wrong. What's dead is jQuery as the default choice for new projects with complex interactive UI. For a form with some validation and a modal, importing React is overkill. $('.form').on('submit', ...) is still sensible in 2026.
What the jQuery era taught us
Abstraction over fragmentation. The browsers were fragmented. jQuery abstracted over the fragmentation and gave developers a stable surface to build on. The lesson: when your environment is fragmented, a well-designed abstraction layer pays enormous dividends. Docker did the same for deployment environments. React Native does it for mobile platforms.
Ecosystem compounds. jQuery's plugin ecosystem made the library worth more than its own code. The value was in the community. Any technology decision today should include "what does the ecosystem look like" alongside the technical properties.
The tool shapes the bugs. jQuery made string concatenation for DOM construction the normal pattern. That pattern caused XSS vulnerabilities at scale. React's JSX made that pattern impossible — you have to opt out of escaping, not into it. The tools you choose determine which mistakes are easy and which are hard.
You don't retire a tool when a better one exists. You retire it when the cost of switching is justified. jQuery-to-React migrations were expensive. Many teams only did them when the jQuery codebase became unmaintainable, not just when React appeared.
We wrote a lot of jQuery code. Some of it was elegant. Some of it was spaghetti that we still think about. All of it worked for what we were building at the time. That's the right criterion.