Question 1

What is an Angular signal?

Accepted Answer

A reactive wrapper around a value that notifies dependents when set or updated. Read with signal(), write with set/update. Templates and computed track reads. Signals are synchronous and fine-grained compared to Zone-driven CD.

Question 2

What is the difference between computed and effect?

Accepted Answer

computed derives a memoized value; effect runs side effects when dependencies change. computed is pure and lazy/cached. effects are for logging, syncing imperative APIs—not for deriving state. Avoid writing to signals in ways that create cycles.

Question 3

How do linkedSignal and resource fit modern Angular?

Accepted Answer

linkedSignal resets/derives writable state from a source; resource manages async data as signals. Use linkedSignal for state that should reset when a parent id changes. resource() standardizes loading/error/value for HTTP. Prefer them over ad-hoc effect patterns.

Question 4

How do you convert an Observable to a signal?

Accepted Answer

Use toSignal(observable, { initialValue }) in an injection context. toSignal subscribes and exposes the latest value. Provide initialValue or requireSync carefully. Unsubscribe is handled when the injection context destroys.

Question 5

How do input() signals differ from classic @Input?

Accepted Answer

input()/input.required() create signal inputs read as this.name() instead of properties. They integrate with computed and are the modern API. model() supports two-way binding. Transform functions can coerce inputs.

Question 6

What are common pitfalls with effects?

Accepted Answer

Using effects to sync derived state, creating write cycles, or running expensive work without untracking. Prefer computed for derived values. Use untracked when reading without subscribing. Keep effects small and intentional.

Question 7

Design a feature store with signals for a product list page.

Accepted Answer

Hold filters/items as signals, expose computed filtered lists, load via resource or service methods updating signals. Keep the store injectable and scoped to the route. Avoid duplicating server state in many components. Expose readonly signals to consumers.

Signals Angular Interview Questions

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