Angular’s computed function creates a derived, read-only signal from existing signals. It replaces much of the mapping work required with RxJS operators and keeps derived data tied to its sources. section 6.4 section 6.8
Pass computed a no-argument callback. The callback’s return value becomes the new signal’s value, and reading source signals inside the callback establishes automatic dependencies. When a dependency changes, Angular recalculates the result; otherwise, the computed value is stored for later reads. section 6.4.1
Deriving a doubled count
A count signal can expose a derived doubleCount signal with computed(() => count() * 2). Incrementing count changes doubleCount automatically, without manually synchronizing a second value. section 6.4.1
Combining multiple signals
computed can read several signals, such as a and b, to create sum. Updating either source causes the sum signal to reflect the new total.
