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`);

}

const text = node.textContent;

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

return {

duration,

tick: (t) => {

const i = ~~(text.length * t);

node.textContent = text.slice(0, i);

}

};

}

</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}