Basic Svelte
Introduction
Bindings
Advanced Svelte
Advanced reactivity
Motion
Advanced bindings
Advanced transitions
Context API
Special elements
<script module>
Next steps
Basic SvelteKit
Introduction
Routing
Loading data
Headers and cookies
Shared modules
API routes
$app/state
Errors and redirects
Advanced SvelteKit
Page options
Link options
Advanced routing
Advanced loading
Environment variables
Conclusion
Svelte ships with several reactive classes that you can use in place of JavaScript built-in objects — namely Map, Set, Date, URL and URLSearchParams.
In this exercise, we could declare date using $state(new Date()) and reassign it inside the setInterval. But a nicer alternative is to use SvelteDate from svelte/reactivity:
App
<script>
import { SvelteDate } from 'svelte/reactivity';
let date = new SvelteDate();
// ...
</script><script lang="ts">
import { SvelteDate } from 'svelte/reactivity';
let date = new SvelteDate();
// ...
</script>previous next
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<script>
let date = new Date();
const pad = (n) => n < 10 ? '0' + n : n;
$effect(() => { const interval = setInterval(() => {date.setTime(Date.now());
}, 1000);
return () => {clearInterval(interval);
};
});
</script>
<p>The time is {date.getHours()}:{pad(date.getMinutes())}:{pad(date.getSeconds())}</p>