You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
svelte/site/content/tutorial/10-transitions/05-custom-js-transitions/text.md

30 lines
684 B

---
title: Custom JS transitions
---
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:
```js
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);
}
};
}
```