Async Preact Signals

When working with signals in Javascript, it is very common to work with async data from Promises.

Async vs Sync

But unlike other state management libraries, signals do not have an asynchronous state graph and all values must be computed synchronously.

When people first start using signals they want to simply add async to the function callback but this breaks how they work under the hood and leads to undefined behavior. ☹️

Async functions are a leaky abstraction and force you to handle them all the way up the graph. Async is also not always better and can have a performance impact. 😬

Working with Promises

We can still do so much with sync operations, and make it eaiser to work with common async patterns.

For example when you make a http request using fetch, you want to return the data in the Promise and update some UI.