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Basic Svelte
Introduction
Reactivity
Props
Logic
Events
Bindings
Classes and styles
Actions
Transitions
Advanced Svelte
Advanced reactivity
Reusing content
Motion
Advanced bindings
Advanced transitions
Context API
Special elements
<script module>
Next steps
Basic SvelteKit
Introduction
Routing
Loading data
Headers and cookies
Shared modules
Forms
API routes
Stores
Errors and redirects
Advanced SvelteKit
Hooks
Page options
Link options
Advanced routing
Advanced loading
Environment variables
Conclusion

In Svelte, an application is composed from one or more components. A component is a reusable self-contained block of code that encapsulates HTML, CSS and JavaScript that belong together, written into a .svelte file. The App.svelte file, open in the code editor to the right, is a simple component.

Adding data

A component that just renders some static markup isn’t very interesting. Let’s add some data.

First, add a script tag to your component and declare a name variable:

App
<script>
	let name = 'Svelte';
</script>

<h1>Hello world!</h1>

Then, we can refer to name in the markup:

App
<h1>Hello {name}!</h1>

Inside the curly braces, we can put any JavaScript we want. Try changing name to name.toUpperCase() for a shoutier greeting.

App
<h1>Hello {name.toUpperCase()}!</h1>

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<h1>Hello world!</h1>