⚡ Deep Dive: Computed Signals in Angular

Computed signals are a powerful feature in Angular’s signal system. They let you create new signals whose values are automatically derived from other signals. This enables you to build complex, reactive UIs with very little code.

A computed signal is a function that returns a value based on one or more other signals. Whenever any of those signals change, the computed signal automatically recalculates and updates the UI.

How This Example Works

• Base Signal: The main counter value is stored in a signal, e.g. count = signal(0);
• Computed Signal: A new signal is created using computed(() => count() + 2). This signal, doubleCount, always reflects count + 2.
• Reactive UI: The template uses 2 to display the computed value. Whenever count() changes, doubleCount() updates automatically.
• No Manual Updates: You never have to set the computed signal yourself. Angular tracks dependencies and updates everything for you.
• Chaining: Computed signals can depend on other computed signals, enabling advanced reactive logic.

Why Use Computed Signals?

• Declarative Logic: Express relationships between values directly in your code.
• Automatic Updates: No need to manually synchronize derived values.
• Performance: Only the parts of the UI that depend on the computed signal are updated.
• Maintainability: Less boilerplate and fewer bugs from out-of-sync state.