Should I use memo?

[rejhgadellaa]

If I have a component that I'm pretty sure should only update when the props change, should I wrap it in memo?

I'm asking because it's located in compat, not in the core, so I'm wondering if Preact has optimizations in place that make memo (more or less) redundant and the addition is just to support the React api?

[rschristian]

You can use it, sure.

To paraphrase Marvin, it's in preact/compat as we think it's not a great API, comparatively. Signals are a much more attractive approach for dealing with unnecessary rerenders, and goes a lot further than memo does. We don't have memo in core because we don't think it's an essential piece, not because it doesn't serve a purpose.

[ackvf]

How would one go about component level memoization with signals then?

[rschristian]

Can you provide an example? Generally you shouldn't need that with signals, the API fundamentally avoids memoization issues.

[ackvf]

Sorry, I am actually asking you for an example how I can use signals to achieve memoization. Surely you didn't mean to store a component in a signal, right?

[rschristian]

Signals themselves are "memoized" (I use this to refer more to the end result/DX than traditional React-flavor memoization) and only update that which subscribes to them. The concept of memoizing components is therefore redundant & unnecessary.

memo is needed to avoid doing additional work when props don't change but signals simply don't trigger that work in the first place. Full component rerenders no longer occur.