Signals — Angular Technical Interview Questions & Answers

Signals

Signals

  • A signal is a value Angular tracks. count = signal(0). Read count() in the template. Update with count.set(1) or count.update(n => n + 1). Don’t do count().n++ on an object — replace or use update.
  • Board: click +1. Template shows the new number. Trap: treating a signal like a plain variable and mutating the inner array without notifying.

Technical Interview Tip: signal(0) + update. No silent mutate.

Code Examples for Signals

Signals — working example

import { Component } from "@angular/core";

@Component({
  selector: "app-root",
  template: `
    <h1>{{ title }}</h1>
    <button (click)="toggle()">Toggle</button>
    <p *ngIf="open">Panel open</p>
  `,
})
export class AppComponent {
  title = "Angular practice";
  open = true;
  toggle() {
    this.open = !this.open;
  }
}

Signals: toggle open. Say whether the panel is on screen after one click.

How to Explain Signals to an Interviewer

How do you change a signal?

set update Not mutate in place