svelte/documentation/tutorial/02-reactivity/03-reactive-statements/text.md

title
Statements

We're not limited to declaring reactive values — we can also run arbitrary statements reactively. For example, we can log the value of count whenever it changes:

$: console.log('the count is ' + count);

You can easily group statements together with a block:

$: {
	console.log('the count is ' + count);
	alert('I SAID THE COUNT IS ' + count);
}

You can even put the $: in front of things like if blocks:

$: if (count >= 10) {
	alert('count is dangerously high!');
	count = 9;
}