Modern web applications are built with frameworks like React almost by default. Whether you're building an online store, a dashboard or a social media platform, there's a good chance React (or another component-based framework) is part of the stack.

But React wasn't created because developers wanted another Javascript library. It was created because the web had reached a point where existing approaches no longer scaled.

In the previous articles in this series, we explored how the web evolved. We saw how Javascript transformed static web pages into interactive experiences, how jQuery simplified DOM manipulation and browser compatibility, and how Single-Page Applications (SPAs) made websites feel more like desktop applications.

Each of these technologies solved an important problem. In doing so, they also made it possible to build larger and more sophisticated applications.

As those applications grew, a new challenge emerged.

Developers no longer struggled to make pages interactive. They struggled to keep increasingly complex user interfaces predictable, consistent and easy to maintain.

React was created to solve that challenge.

The problem wasn't updating the DOM

One of the biggest misconceptions about React is that it was created because updating the DOM was slow. That wasn't the real problem.

Libraries like jQuery had already made DOM manipulation straightforward.

$("#username").text("Duke");
$("#login-button").hide();
$(".notification").addClass("success");

Updating an element was easy. The difficult part was knowing which elements needed to be updated after the application's state changed.

As web applications grew, different parts of the interface also started sharing the same data. A user's profile information could appear in the navigation bar, account menu, comments, chat messages and activity feed all at once.

User updates profile
        ↓
Application state changes
        ↓
→ Navigation bar
→ Account menu
→ Comments
→ Chat
→ Activity feed

Keeping all of these views synchronized became increasingly difficult. Before React, developers had to manually update every affected part of the interface whenever the application's state changed. This approach worked for small websites, but as applications grew, it became one of the biggest sources of bugs.

Updating one element was easy.

Updating every element that depended on the same data wasn't.

State became the real challenge

But what had changed? Why did keeping the interface synchronized become so difficult?

Because modern web applications had to manage far more state than traditional websites ever did.

A page no longer displayed static content. It had to remember whether a user was logged in, what products were in their shopping cart, which notifications had been read and what information had already been entered into a form.

Instead of rebuilding the page after every request, applications remained active and continuously responded to user input. Every change to that state had to be reflected everywhere the data was being displayed.

The more state an application managed, the harder it became to keep the entire interface synchronized.

React introduced a different way of thinking

Instead of telling the browser exactly how to update the page, React asked developers to describe what the interface should look like for the current application state.

When that state changed, React compared the new UI with the previous one and applied the DOM updates needed to reflect the change.

Instead of writing code like:

Find this element.
Change its text.
Hide this button.
Show that message.
Update this counter.

Developers could simply think:

Current application state
        ↓
What should the user see?

This shifted the focus from manually updating the interface to describing the desired result. React handled the process of keeping the DOM synchronized, an approach known as declarative programming.

Rather than changing how developers manipulated the DOM, React changed how they thought about building user interfaces.

This may sound like a subtle difference, but it fundamentally changed how developers built applications.

Instead of manually updating every affected part of the page, developers described how each component should render for a given application state. React then handled translating those changes into the necessary DOM updates.

This reduced the amount of manual synchronization developers had to write, making large applications easier to build and maintain.

Components made large applications easier to manage

React also encouraged developers to split user interfaces into small, reusable components. Instead of treating an entire page as one large block of HTML and Javascript, each part of the interface became an independent building block with its own responsibility.

For example, an online store might be structured like this:

<App>
 ├── <Navbar />
 ├── <SearchBar />
 ├── <ProductList />
 │      └── <ProductCard />
 ├── <ShoppingCart />
 └── <Footer />

Each component described one part of the interface and could be developed, tested and maintained independently. Components could also be reused across different pages, reducing duplication and making future changes much easier.

This approach made large applications easier to understand. Rather than navigating a single file containing thousands of lines of code, developers could focus on one component at a time.

The Virtual DOM wasn't the main innovation

This new way of building user interfaces raised an obvious question: how could React update the page efficiently without developers manually manipulating the DOM?

Much of the early discussion focused on the Virtual DOM. Many developers assumed this was the reason React became so successful because it appeared to solve one of the web's biggest performance concerns: avoiding unnecessary DOM updates.

The Virtual DOM was an important optimization, but it wasn't React's biggest innovation.

React's real innovation was its programming model. Developers described how the UI should look for a given application state, while React handled the process of comparing the new UI with the previous one and applying only the DOM changes that were actually needed.

The Virtual DOM was simply the mechanism that made this approach efficient. Even without it, the idea of building interfaces declaratively and organizing them into components would still have fundamentally changed front-end development.

React changed front-end development

React didn't just introduce a new API or a faster way to update the DOM. It popularized a different way of building front-end applications.

Concepts like components, declarative rendering and state-driven user interfaces became the foundation of modern front-end development. Today, frameworks such as Vue, Svelte, Solid and even newer versions of Angular embrace many of the same ideas, even though they implement them differently.

React also influenced the wider ecosystem. State management libraries, routing solutions, testing tools and design systems were all built around the component model, making it easier to develop large applications as teams and codebases grew.

Today, thinking in components and describing the UI as a function of state feels completely natural.

Before React, it wasn't.

Looking back

React wasn't created because developers needed another Javascript library.

It was created because web applications had become too complex to manage through manual DOM updates alone.

By introducing a declarative, component-based approach, React made large, state-driven applications easier to build, understand and maintain. The Virtual DOM helped make this practical, but it was the programming model that changed how developers thought about user interfaces.

Today, those ideas have become the standard across modern front-end development.

React was the next step in the web's evolution.

Common misconceptions

React replaced Javascript

No. React is a Javascript library.

Every React application is still written using Javascript (or Typescript).

React made the DOM fast

Not exactly. Manipulating the DOM wasn't the biggest challenge.

Managing increasingly complex user interfaces was.

React's biggest innovation was providing a better way to describe and organize those interfaces.

React invented components

No.

Component-based development had existed for many years in technologies such as Java Swing and Microsoft's .NET frameworks.

However, React popularized the idea and made it practical for large-scale web applications.

You must use React to build modern websites

No. Many websites don't need React at all.

Traditional server-rendered applications are often simpler, faster and easier to maintain.

React is most valuable when building highly interactive applications with lots of shared state.

React replaced jQuery overnight

Not at all. For many years, both libraries coexisted.

Many applications even used jQuery alongside React during gradual migrations.

React didn't make jQuery obsolete overnight—it addressed a different set of problems as web applications became increasingly complex.

Frequently asked questions

Did React replace Javascript?

No.

React is a Javascript library, not a replacement for the language itself. Every React application is still written using Javascript (or Typescript), and understanding Javascript fundamentals is essential for using React effectively.

In fact, React builds upon Javascript features such as functions, objects, modules and closures rather than replacing them.

Is React a framework?

Not officially.

React describes itself as a Javascript library for building user interfaces. Its primary responsibility is rendering the UI based on your application's state.

Unlike full frameworks, React doesn't include built-in solutions for routing, state management or data fetching. Developers typically choose those tools separately, although modern frameworks like Next.js build on top of React to provide a more complete development experience.

Does React make websites faster?

Not necessarily.

React wasn't created because websites were slow.

It was created because building and maintaining complex user interfaces had become difficult.

In some cases React can improve performance by updating only the parts of the page that have changed. In other cases, a simple server-rendered website with little Javascript may actually load faster than a React application.

The biggest benefit of React is improving the developer experience and making large applications easier to maintain.

React solved a problem that many developers were experiencing.

As applications became larger, manually keeping the UI synchronized became increasingly difficult. React introduced a simpler mental model: describe what the interface should look like for the current application state, and let React handle updating the DOM.

Its component-based architecture, strong ecosystem and backing from Facebook also contributed to its rapid adoption.

Today, many of the ideas React popularized have influenced nearly every modern front-end framework.

Is React still relevant today?

Yes.

React remains one of the most widely used libraries for building modern web applications, powering products used by millions of people every day.

The ecosystem has evolved significantly since React was first released. Features such as Hooks, Server Components and modern frameworks like Next.js have changed how React applications are built.

Even if another framework eventually becomes more popular, React's lasting impact isn't tied to its market share.

It changed how developers think about building user interfaces. Concepts such as declarative rendering, reusable components and state-driven interfaces have become standard practices across modern front-end development.

Explore the series

I wasn't building websites when the web was just HTML or when Javascript didn't exist. Like many developers, I learned modern frameworks first and only later became curious about how we got here.

This series is my way of connecting those dots. By looking back at the problems developers faced and the solutions they created, it becomes much easier to understand why today's tools exist and why the web evolved the way it did.