React has long been the darling of web and app developers for its component-based architecture that speeds up development, and now Svelte is gaining a lot of attention for its performance and ease of use. So which one is best for your project?  

This article explores the technical benefits of Svelte vs. React, explains their origins and purposes, and discusses the critical factors you must consider when choosing a frontend library, including performance, ease of learning/adoption, and the developer tools around them. 

What is React, and how does it work? 

React is a free and open-source component-based frontend JavaScript library for declaratively building interactive user interfaces (UIs). React focuses on rendering the UI and keeping the Document Object Model (DOM) up to date with the application state. 

React efficiently updates and renders only the relevant components (React's system of splitting up UI elements into reusable blocks) when data for display changes. React's encapsulated components manage their own state, and you can compose them to make complex UIs. 

React is able to render the UI efficiently through the use of a virtual DOM. React creates an in-memory representation of the DOM that caches its state, then when changes happen, it computes the resulting differences on the virtual DOM, and then updates the browser’s displayed DOM. This approach avoids the costly process of recalculating CSS styles and layout for the entire page, and only updates the subcomponents that have been changed. 

Because React is only concerned with building the UI, and does not provide the foundation to build a complete application, it is considered a library (rather than a framework). It must be integrated with other libraries for things like loading or storing data and page routing — giving you flexibility in how you develop applications.

You build React components using a declarative syntax called JSX (JavaScript Syntax Extension), an extension to the JavaScript language syntax that looks similar in appearance to HTML. JSX allows you to create using more intuitive and expressive code, while reducing the cognitive load required to understand the underlying logic of the components.

Above is an example of JSX being used in a React component.

React also supports server-side rendering, which allows you to render your React components on the server and send the resulting HTML to the client. This can be useful for improving the performance of your application, as well as for search engine optimization (SEO) and a better user experience.

What is Svelte, and how does it work?

Like React, Svelte is a free and open-source component-based frontend JavaScript tool for declaratively building interactive user interfaces. Svelte is considered a framework (as opposed to a library, like React) as it offers more structure and more built-in functionality. This doesn't make it better; it’s just a different approach to building applications with premade components. 

Svelte is optimized for performance, and does not use a virtual DOM. With React's virtual DOM, the web browser must do extra work to convert its component structures for display at runtime (that is, as the user is using your web page or app). Svelte, on the other hand, compiles your code at build time, before it is deployed. 

This build process creates highly optimized client-side JavaScript that directly manipulates the DOM. This eliminates the parts of the framework that are unnecessary for your app, resulting in a smaller bundle with no external dependencies, faster initial load times, and improved performance.

Svelte uses an HTML-like syntax for describing UI, which is much closer to vanilla HTML than JSX is, but with some syntactic sugar added for extra capabilities. This includes components that use standard CSS that is scoped to the component by default, eliminating issues with the CSS cascade (such as conflicting classes). You can still employ global styles, and you can also use popular CSS libraries such as Tailwind CSS. 

This simplicity makes it easy to learn, particularly for those who are already familiar with HTML and CSS. Svelte’s compiler approach allows you to write components in a very concise and expressive manner while still producing very efficient applications. 

Additionally, Svelte has great built-in support for TypeScript, which makes it easier to write type-safe, maintainable code. Like React, Svelte also supports server-side rendering (which is part of SvelteKit's behavior, discussed later in this article).

Why do developers choose React?

React is the most popular JavaScript library for building user interfaces. The evidence is plain to see in the 2024 Stack Overflow Developer Survey, 2023 State of JS survey, and 2022 Jamstack Community Survey.

How did React become so popular?

When React was released in 2013, it pulled together many good parts of existing libraries and frameworks into one package and added some technical features that were unlike anything else that existed at the time. These factors were instrumental in its rise to the top, and include:

• Easy creation of dynamic applications: React simplifies the process of creating dynamic web applications compared to vanilla JavaScript, which can become complex quickly.

• Improved performance: With the virtual DOM, React makes applications faster by updating only the items that were changed, instead of updating all components as traditional web applications did. 

• Reusable components: Components are the building blocks of any React application, with a single app often comprising multiple components. These components encapsulate their logic and controls, which can be reused throughout the application, resulting in dramatically reduced development time.

• Unidirectional data flow: React follows a unidirectional data flow. This means that when designing a React app, developers often nest child components within parent components. As a result, it becomes easier to debug errors and locate where a problem occurs in an application at the moment in question.

• Web and mobile app development: While React is commonly used for web applications, it can also be used to create mobile applications using a library called React Native. Since React is only concerned with creating user interfaces and not so much about the render target, that render target can be a mobile app. 

• Dedicated debugging tools: React ships a first-party browser extension that can be used to debug React applications. This makes debugging React web applications fast and easy.

Why do developers continue to use React?

The broad adoption of React has resulted in important, non-technical advantages for developers, driven by its large and engaged community: 

• The ecosystem: The React community has developed an enormous ecosystem of libraries and tools to extend React. You can pretty much install anything to do anything in React. Not to mention all the sub-ecosystems like Next.js, React Query (TanStack Query), etc. that are building sub-ecosystems within the React ecosystem. 

• Adoption: Look at any adoption curve online on any survey for frontend UI frameworks right now, and I can guarantee you that React (or some library built on React) will be at the top. Its first-mover advantage has put it so far ahead that it will be difficult to unseat.

• Job market: React developers are in demand, so new and aspiring developers learn React and increase its adoption. These are the people who will make decisions about tech stacks in their companies, and they are likely to use what they have the most experience with, further driving adoption.

• Cost of switching: Many of the benefits of competing frameworks are minuscule compared to the cost of switching a project from React (and having to learn the syntax and tools for a new library or framework). For most developers, React is good enough, especially when they have bigger issues to deal with.

• Backing of a big tech company: React rode on the popularity and support of Meta (formerly Facebook), which drove its rapid growth. Everyone wanted to jump on the trend, and that created many React developers, which contributed to its continued popularity.

• Popularity: People use React because other people use React and that virtuous cycle keeps its popularity going. Popularity has a network effect that creates more popularity.

These factors make React a sensible choice for any project that requires a stable, well-supported user interface library — especially given its broad adoption by big-name software companies who will continue to develop and maintain it.

Is Svelte better than React?

If I had to advise a prospective frontend developer right now who wants to figure out what to learn, I’d recommend React. It’s popular, there are many jobs available, there’s a vibrant community backing a massive ecosystem, big companies use it, and big startups are building on top of it. 

However, React has its pain points, and developers with specific goals or who are already well-versed in React may want to look for new tools that can do certain things better. Svelte is one of these — it offers a different approach to frontend development than React, with headlining features that include:

• Small bundle, faster apps: One of Svelte’s biggest strengths is its small JavaScript bundle sizes. Because Svelte is a compiler, you always get the minimum subset of features required by your app. For example, the Svelte implementation of the TodoMVC is 3.6kB zipped. For comparison, React plus ReactDOM with no app code is a whopping 45kB zipped. Even if your app is only made of one component, you still have to serve the 45kB that is React itself. This makes Svelte ideal for creating high-performance applications that load quickly, even when mobile connections (or devices) might be a bit slow. 

• Easier to learn: Svelte feels like a natural next step if you’ve been learning HTML, CSS, and JavaScript. This makes it easy to collaborate with people who have a basic understanding of CSS and HTML. If you know HTML and CSS, you can write Svelte immediately. You can then learn more as you go, layering new concepts on top of that. Being close to regular old HTML also means it is a much easier on-ramp into using UI frameworks in general compared to React.

• Batteries included: Unlike React, Svelte comes with essential functionality beyond just building UIs. While React has tons of external libraries to extend it, it’s nice to work with a framework where you don’t have to be making decisions at every turn about what to use. To be fair to React, there are some things React has first-party that Svelte relies on external libraries for, such as DevTools and Mobile/Native. 

Svelte doesn't have the level of adoption that React does, but that doesn't mean that you shouldn't consider it if you are starting a new project. There are some other major features that are making Svelte increasingly popular, including simplified state management, reactivity, and statically scoped styling.

Simplified state management in Svelte

Svelte state management is much simpler compared to React’s state management libraries. Svelte stores are JavaScript objects that allow data or functionality to be shared between multiple components to manage the application state — by allowing components to subscribe to any changes in the store. 

Svelte stores adhere to a simple interface with a subscribe method that returns an unsubscribe function. They update your components whenever their data changes, and they allow for separation of the state management from the component hierarchy. This is important when the same piece of data is needed in more than one place. 

Creating and using stores in Svelte doesn't require external libraries, and can be implemented in a few lines of code. First, you need to create a store:

Then, you can read and write to it from a component. You don't even have to explicitly subscribe to the store; Svelte handles it automatically:

In the above Svelte snippet, the value stored in counter is directly manipulated using the reactive statement $counter — so it can be incremented, as it is a numerical value, and it will be updated in both the DOM and the store automatically.

Leaner code with reactivity in Svelte

When a variable or store changes, Svelte automatically updates the DOM at runtime thanks to its built-in reactivity. It does this by using mutable variables to manage local state. This makes for leaner code. 

Here’s a Svelte counter component:

This looks a lot like a regular HTML file; however, Svelte is clever enough to know that whenever the value of the count variable (i) changes, all the values that reference it should change as well, including any elements in the DOM. Because it's assigned in a script block, reactivity is assumed. Updating a value, and all the things that depend on it, is achieved simply by using the assignment operator (=). 

For comparison, here’s the same thing in React:

This React code is much more complex to both write and understand, demonstrating how Svelte can streamline development.

Simplify prevention of CSS conflicts with static scoped styling

Svelte offers static scoped styling, using just CSS, with no need for CSS-in-JS solutions. By adding a style tag in a component and writing CSS, Svelte automatically scopes that CSS to that specific component. While this is possible in React, it requires additional code or libraries.

Transitions and animations in Svelte

Svelte includes built-in support for transitions and animations (like fading, blurring, sliding, crossfading, and scaling). React, again, would require additional code or libraries to implement these.

More abstraction than React

Svelte’s syntax provides a pleasant developer experience by abstracting some of the pain that its predecessors had. For example, forms can be complex to implement in React. That’s why libraries like Formik and React Hook Form exist. 

A form in React would look something like this:

Whereas in Svelte, the code is more concise and easier to follow:

Svelte vs. React interoperability 

Svelte allows you to use any npm or yarn library — Svelte apps are just JavaScript. Even though the ecosystem of dedicated Svelte packages and plugins is relatively small, you can use any framework-agnostic package with Svelte and it can contribute to all the other ecosystems. In contrast, React requires React-specific libraries that work with its virtual DOM.

Svelte encourages progressive enhancement

Svelte encourages you to follow the progressive enhancement design philosophy when building applications. This results in more robust apps that can still function even without JavaScript. 

Progressive enhancement prioritizes core functionality and accessibility, ensuring that everyone can access content and features regardless of the technology they use. Therefore, Svelte apps are less reliant on JavaScript, making them more resilient to older browsers and slower connections.

Svelte vs. React performance, complexity, and other factors compared

All of this is great, but this doesn't make Svelte better — each product has its advantages and use cases where it shines.

Here’s a matrix for a quick comparison:

As a relatively new framework, Svelte is currently facing some challenges. One of these challenges is a limited library ecosystem, so there are fewer options and less mature external libraries available. Depending on the specific project and team, this could be a minor inconvenience or a major obstacle to development. 

Consequently, while Svelte is easier to learn, adopting it can be more challenging than adopting React, as Svelte users must solve problems that other communities have already established solutions for. However, as Svelte continues to gain more adoption, these problems will continue to diminish.

It's also worth noting that React does have a compiler on the way, but it's not yet production-ready, and its performance will still be reliant on the virtual DOM.

Who's using React?

React is widely used in application front ends, including:

• Instagram

• Airbnb

• Netflix

• Contentful

The use of React in big-name apps and websites isn't a sign of its superiority, however — it's a sign of its longevity and popularity.

Who's using Svelte?

Svelte is targeted at high-performance applications. Examples of popular products built with Svelte include:

• Apple Music's web interface

• Spotify's Artist Dashboard

• New York Times' interactive articles

• Rakuten ecommerce platform

Svelte is being increasingly adopted across different industries due to the advantages discussed above, but this does not mean it is displacing React as the most popular JavaScript tool for building front ends (at this stage).

React vs. Svelte: Which one should you choose?

The decision on whether to use React or Svelte to build your application front ends will largely depend on what you're trying to achieve.

Deciding which to learn: React vs. Svelte

If your priority is an easy-to-learn tool for building interactive UIs or gaining experience, Svelte is a highly regarded option. 

Svelte ranks second in retention, interest, usage, and awareness among frontend frameworks in the 2023 State of JavaScript survey, now ranking #4 in popularity, behind Angular. However, if your goal is to land a job in the industry, React is the more widely used framework and offers more job opportunities.

Deciding whether you should use React or Svelte for your project

For new startups or projects, Svelte can provide faster development and better performance, but finding developers who are experienced with it may be challenging, as its community is smaller compared to React, Vue, and Angular. However, if you are already familiar with another JavaScript framework, learning Svelte should be straightforward, and vice versa.

React is less opinionated than Svelte, coming with less built-in functionality and a more flexible structure. This may be more attractive for some projects that don't quite fit with Svelte's way of doing things (sensible though it is for most use cases), or that will require a specific library that already includes support for React.

Despite having a smaller user base than other frameworks, Svelte is gaining popularity and is now being mentioned alongside React, Vue, and Angular. Svelte’s growing community makes it a good option for early adopters who want to contribute to its ecosystem. Other frameworks are also taking cues from Svelte, leading to synergies in the communities.

What about SvelteKit?

SvelteKit takes Svelte from a user-interface framework to a full application framework. It provides everything from routing to server-side rendering, data fetching, and support for creating static and dynamic websites.

SvelteKit is an ideal tool if you want to further minimize the amount of code you need to write. You can get started with SvelteKit fast using the SvelteKit Starter with Contentful.

Svelte vs. React: Choose what's best for your individual project 

While Svelte has many technical merits that make it superior to React, technical excellence alone is not enough to make a technology mainstream. Social proof, timing, and network effects are also critical factors, all of which React currently has in its favor.

In addition to the technical differences when weighing Svelte vs. React, another consideration for developers is the compatibility of these libraries with other technologies. Of particular relevance here is compatibility with content management systems. Contentful works smoothly with any framework, so regardless of which one you choose, you can expect a great developer experience.

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