Svelte is a JavaScript framework that shifts work from the browser to a compile step. Created by Rich Harris, it produces highly optimized vanilla JavaScript, eliminating the runtime overhead of traditional frameworks.
Key Innovation
Unlike React or Vue, Svelte is a compiler:
- No virtual DOM: Direct DOM updates at runtime
- No framework runtime: Ships vanilla JavaScript
- Compile-time reactivity: State changes become surgical DOM updates
- Smaller bundles: No framework code included
How It Works
Svelte compiles declarative component code into efficient imperative JavaScript. When you write count += 1, Svelte generates code that updates exactly the DOM elements that need changing.
Key Features
Svelte provides modern framework features without runtime cost:
- Reactive declarations:
$:marks statements that rerun when dependencies change - Scoped styles: CSS scoped to components by default
- Built-in animations: Transitions and animations as first-class features
- Stores: Simple reactive state management
SvelteKit
SvelteKit is Svelte’s application framework, providing:
- Server-side rendering
- Static site generation
- File-based routing
- API endpoints
Impact
Svelte challenged assumptions about how frameworks work. Its compile-time approach influenced other frameworks and raised questions about runtime overhead that was previously accepted.