svelte/site/content/tutorial/05-events/04-component-events/text.md

title
Component events

Components can also dispatch events. To do so, they must create an event dispatcher. Update Inner.svelte:

<script>
	import { createEventDispatcher } from 'svelte';

	const dispatch = createEventDispatcher();

	function sayHello() {
		dispatch('message', {
			text: 'Hello!'
		});
	}
</script>

createEventDispatcher must be called when the component is first instantiated — you can't do it later inside e.g. a setTimeout callback. This links dispatch to the component instance.