`computed()`

Derives a memoized read-only signal from other signals.

Since Angular 16+ Spec ↗

Syntax

computed<T>(computation: () => T, options?): Signal<T>

Parameters

Name	Type	Required	Description
`computation`	`() => T`	No	Function whose return value becomes the derived signal value.
`options`	`object`	No	Optional config; supports an equal comparator function.

Returns

Signal<T> — A read-only signal recomputed lazily when its dependencies change.

Examples

import { signal, computed } from '@angular/core';

const price = signal(100);
const qty = signal(3);
const total = computed(() => price() * qty());
console.log(total()); // 300

const firstName = signal('Ada');
const lastName = signal('Lovelace');
const fullName = computed(() => `${firstName()} ${lastName()}`);

Notes

Computed signals are lazy and memoized: the computation only runs when read and when a tracked dependency has changed. They are read-only — you cannot call set() or update() on them. Only signals read during the computation become dependencies.