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Comment by davedx | Hacker News Reader

For sure. Look at this Svelte 5 example:

  $effect(() => {
    const timer = setInterval(() => {
      time = new Date().toLocaleTimeString();
    }, 1000);

    return () => clearInterval(timer);
  });

</script>

<p>Current time: {time}</p>

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This example is a bit strange to me. I wonder if `$effect` will actually replace all usage of `onMount` and `onDestroy` for Svelte. In Solid you could totally do these things with `useEffect` too, but they chose to keep `onMount` and `onDestroy` (which they call `onCleanup`) to make this kind of thing more simple.

Example: https://www.solidjs.com/examples/counter

`onMount` and `onDestroy` feel like really useful, dependable callbacks. `$effect` is scary because if you add a reference to state in it, you can't depend on it being called like `onMount`.

They don't claim they'll remove `onMount`.

They claim most (but not all) of current usage of `onMount` will be better off using `$effect` instead

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