Svelte • Introduction

Overview

Svelte is a framework for building user interfaces on the web. It uses a compiler to turn declarative components written in HTML, CSS and JavaScript…

<script lang="ts">
	function function (local function) greet(): voidgreet() {
		function alert(message?: any): voidwindow.alert() instructs the browser to display a dialog with an optional message, and to wait until the user dismisses the dialog.
MDN Referencealert('Welcome to Svelte!');
	}
</script>

<button onclick={function (local function) greet(): voidgreet}>click me</button>

<style>
	button {
		font-size: 2em;
	}
</style>

<script>
	function function (local function) greet(): voidgreet() {
		function alert(message?: any): voidwindow.alert() instructs the browser to display a dialog with an optional message, and to wait until the user dismisses the dialog.
MDN Referencealert('Welcome to Svelte!');
	}
</script>

<button onclick={function (local function) greet(): voidgreet}>click me</button>

<style>
	button {
		font-size: 2em;
	}
</style>

…into lean, tightly optimized JavaScript.

You can use it to build anything on the web, from standalone components to ambitious full stack apps (using Svelte’s companion application framework, SvelteKit) and everything in between.

These pages serve as reference documentation. If you’re new to Svelte, we recommend starting with the interactive tutorial and coming back here when you have questions.

You can also try Svelte online in the playground or, if you need a more fully-featured environment, on StackBlitz.