Deferring effect triggering

[predaytor]

Solid.js has a on utility that allows you to explicitly define dependencies with the option to defer until the next value changes. Maybe we have something similar for @preact/signals?

const [a, setA] = createSignal();

// doesn't run immediately
createEffect(on(a, (v) => console.log(v), { defer: true }));

setA("new"); // now it runs

[rschristian]

You can pretty easily support this with a simple initialized value:

import { signal, effect, useSignalEffect } from '@preact/signals';

const count = signal(0);
const initialized = signal(false);

effect(() => {
	count.value;
	if (!initialized.peek()) return initialized.value = true;
	console.log(count.value);
});

count.value++;

This does get more complicated the more an effect does, but we'd encourage users to keep effects small.

Edit: initialized as a signal might be overkill, depends on what you're doing. Standard variable (let initialized = false) can be fine too.

[predaytor]

thx!