JavaScript has been essential for creating appealing web content for a long time. However, to take advantage of it, web developers first had to master the programming language, which is something that not everyone had the time or desire to do. Now, there are frameworks that allow developers to execute JavaScript functions, even complicated ones, automatically. This reduces the amount of programming work significantly. At the same time, most frameworks place a heavy load on the browser. In this respect, Svelte is a fundamentally new approach.

What is Svelte?

Svelte (also referred to as Svelte JS) is also a framework for developing JavaScript apps. As such, it provides the basic framework for the final application and important, frequently used functions as automatically integrated libraries. Within a given framework, it defines the basic options in addition to fundamentally determining the development process. Frameworks used in programming web applications are easy to use after a short familiarisation period.


JavaScript (abbreviated as JS) is a scripting language that expands the options provided by standard HTML and CSS and can be interpreted by all modern web browsers. It can be used to create interactive web pages and web apps. Despite its name, JavaScript has little in common with the high-level programming language Java.

Svelte is an ideal tool for creating fast web applications and is similar in its core concept to other Javascript frameworks, such as Angular, Vue, Ractive and React. Similar to these frameworks, Svelte is based on JavaScript and enables you to create interactive user interfaces. However, the generated code is much leaner than that of traditional frameworks.

What are the advantages of using Svelte?

Svelte’s core innovation is the ability to convert complex framework code into simple optimised JavaScript. Most prior frameworks have left it up to the browser to interpret and display apps in JavaScript. This results in the display being rendered more slowly. In contrast, Svelte compiles the app into lean optimised JavaScript during development. One goal in the development of Svelte was to enable web developers themselves to write code that is as lean and elegant as possible without needing to burden the framework.

How is Svelte different from other frameworks?

The problem with traditional frameworks is always the same. Instead of simplifying JavaScript code to make it work well in a browser, they extend the code and let JavaScript interpret all the framework’s functions - often even unused ones. As a result, even comparatively small applications inflate into large scripts when using a traditional framework requiring computing time and data to execute. In short, frameworks help to structure thoughts but not code. The problem is often that framework developers are focused on execution in the browser and overlook the use of pure “vanilla” JavaScript. This is the main difference between Svelte and other traditional frameworks. Apart from a few basic commands, which are very easy to learn, Svelte uses pure HTML, CSS, and JavaScript.


CSS (Cascading Style Sheets) is a simple language which describes the visual layout of a HTML page. While HTML code only contains the actual content, the page can be displayed differently on various platforms by changing the CSS.

During the development process, the app’s components are compiled into self-contained JavaScript modules. Programmers can check the stability and execution of their compiled program in a preview window at any time. The advantage of this approach is that the final script becomes lean and fast. Using Svelte, you can avoid the virtually uncontrollable bloating that occurs in scripts written in traditional frameworks. This leads to performance that is up to 10 times faster than, for example, the previously widely used React framework.

Svelte JS architecture

Svelte JS (JavaScript) consists of multiple components. Its unique appeal lies in the fact that the web developer barely has to worry about the CSS components which are both cumbersome and error-prone. All they need to do is define the HTML or XML tags and let Svelte JS interpret them. Svelte JS then creates the app’s components itself. The HTML code is written in a REPL (read-eval-print loop) command window in the browser. JavaScript interprets it immediately and automatically. This allows the code’s stability to be tested immediately.

What is the optimal use for Svelte?

With its simple minimalistic approach, Svelte enables a broad extension of web apps. While React requires virtually the entire script to be established from the beginning, Svelte allows you to add extensions later on without compromising the stability or performance of the app. This makes Svelte an ideal tool for developing new apps and improving the performance of existing structures. The developers of Svelte JS are primarily targeting beginners to app programming. They offer starter kits which can be used to get results very quickly. Svelte JS does require some prior knowledge, especially in CSS and JavaScript. However, the lean approach of the Svelte framework makes it easy for beginners to find their way around the programming environment.

How to install Svelte JS or try it online

To install Svelte JS locally on your system, Node.js must be installed. Then, you can install Svelte JS from the GitHub repository.

git clone
cd svelte
npm install

The Svelte JS programming environment runs on a local web server at “http://localhost:5000”. The online demo page for Svelte introduces it without needing to install the program package. It provides example scripts for all important components which can be modified and tested interactively with the original REPL tool. This allows you to assess quickly whether or how Svelte JS may be suitable for implementing your app idea.

Outlook: Svelte as the universal standard for apps?

Svelte JS enables you to create faster and more powerful apps than traditional frameworks due to the large reduction in data used. However, Svelte is still quite new on the scene and only has a small community of users. Svelte JS promises better access, easier onboarding and faster results. So far, it has kept these promises. If Svelte JS really turns out to be that much more powerful than Vue, Ractive or React, it might soon replace them and become the new universal standard for mobile web app development.

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