svelte/documentation/examples/05-bindings/04-textarea-inputs/App.svelte

<script>
	import { marked } from 'marked';
	let text = `Some words are *italic*, some are **bold**`;
</script>

<textarea bind:value={text} />

{@html marked(text)}

<style>
	textarea {
		width: 100%;
		height: 200px;
	}
</style>