StateAdapt

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Function: toSignal() ​

toSignal<State>(source$, __namedParameters): Signal<State>

Defined in: libs/angular/src/lib/to-signal.function.ts:67

Converts an observable to a signal without keeping the source observable subscribed to when no Angular consumer is reading the signal.

Signals created in a component, directive, or locally provided service are subscribed to immediately and unsubscribed from with that view. Signals created in a root injection context are subscribed to only while a template or effect keeps reading them.

Example: Basic usage ​

ts
import { Injectable } from '@angular/core';
import { toSignal } from '@state-adapt/angular';
import { interval } from 'rxjs';
import { map } from 'rxjs/operators';

@Injectable({ providedIn: 'root' })
export class RandomService {
  random$ = interval(1000).pipe(map(() => Math.random()));
  random = toSignal(this.random$, { initialValue: 0 });
}

Example: Initial value factory ​

initialValue can be a function that returns the value. The signal calls it when it subscribes, keeps that value until it unsubscribes, and discards it then—so the factory runs again for each subscription.

ts
import { Injectable } from '@angular/core';
import { toSignal } from '@state-adapt/angular';
import { interval } from 'rxjs';
import { map } from 'rxjs/operators';

@Injectable({ providedIn: 'root' })
export class RandomService {
  random$ = interval(1000).pipe(map(() => Math.random()));
  random = toSignal(this.random$, { initialValue: () => Math.random() });
}

A read while the signal is unsubscribed will not use a cached value, but call the factory function.

Type Parameters ​

State ​

State

Parameters ​

source$ ​

Observable<State>

__namedParameters ​

ToSignalOptions<State>

Returns ​

Signal<State>