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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

While you should generally use CSS for transitions as much as possible, there are some effects that can’t be achieved without JavaScript, such as a typewriter effect:

App
function typewriter(node, { speed = 1 }) {
	const valid = node.childNodes.length === 1 && node.childNodes[0].nodeType === Node.TEXT_NODE;

	if (!valid) {
		throw new Error(`This transition only works on elements with a single text node child`);
	}

	const text = node.textContent;
	const duration = text.length / (speed * 0.01);

	return {
		duration,
		tick: (t) => {
			const i = Math.trunc(text.length * t);
			node.textContent = text.slice(0, i);
		}
	};
}

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<script>
	let visible = $state(false);
 
	function typewriter(node, { speed = 1 }) {
		const valid = node.childNodes.length === 1 && node.childNodes[0].nodeType === Node.TEXT_NODE;
 
		if (!valid) {
			throw new Error(`This transition only works on elements with a single text node child`);
		}
 
		return {};
	}
</script>
 
<label>
	<input type="checkbox" bind:checked={visible} />
	visible
</label>
 
{#if visible}
	<p transition:typewriter>
		The quick brown fox jumps over the lazy dog
	</p>
{/if}