Svelte

Svelte is a modern frontend framework that takes a unique approach to building user interfaces. Rather than using a virtual DOM, Svelte shifts much of the work to compile time, converting your components into efficient imperative code that updates the DOM directly.

Core Concepts

Compiler-Driven Framework

Compilation: Svelte compiles your components during build time, producing optimized JavaScript with minimal runtime overhead.
No Virtual DOM: Instead of diffing and patching a virtual DOM, Svelte updates the actual DOM directly, resulting in improved performance.

Reactive Declarations

Reactivity: In Svelte, reactivity is achieved with simple assignments. When a variable's value changes, the UI updates automatically.
Reactive Statements: Use the $: syntax to create reactive statements that re-run whenever their dependencies change.

<script>
  let count = 0;
 
  // Reactive declaration: updates whenever `count` changes
  $: doubled = count * 2;
</script>
 
<p>Count: {count}</p>
<p>Doubled: {doubled}</p>
<button on:click={() => count += 1}>Increment</button>

Single-File Components

Component Structure: Svelte components are written in single .svelte files that encapsulate HTML, JavaScript, and CSS.
Scoped Styles: CSS defined within a Svelte component is scoped by default, reducing the risk of style conflicts across components.

<style>
  p {
    color: blue;
  }
</style>
 
<script>
  export let name = "World";
</script>
 
<p>Hello, {name}!</p>

Tooling and Ecosystem

SvelteKit: The official framework for building Svelte applications, offering features such as file-based routing, server-side rendering, and more.
Developer Experience: Svelte's simple syntax and powerful reactivity model make it accessible to both beginners and experienced developers.
Community: A growing ecosystem with an increasing number of plugins, integrations, and resources.

Additional Resources

Vue Next.js