Angular Signals

Angular Signals: Basics and Managing Signal Values

Learning Outcome

5

Understand reactivity in Angular (without RxJS)

4

Explore methods for updating signals

3

Update and manage signal values

2

Learn how to create and use signals

1

Understand Angular Signals

Analogy

Think of a live cricket scoreboard :

Analogy

Mapping :

Signal = score value

Update = new runs added

UI = scoreboard display

Whenever the signal changes, UI updates automatically —
just like a live scoreboard.

Why Angular Signals

RxJS Observables

Zone.js

Change Detection mechanism

Traditional Angular uses :

Challenges :

Complex state management

Hard to track data changes

Performance overhead in large apps

Provide simple reactive state management

Automatically update UI when data changes

Remove need for manual subscriptions

Improve performance with fine-grained updates

Managing UI state

Replacing simple RxJS use cases

Writing cleaner and readable code

Signals are ideal for :

Angular Signals Solve This :

 What are Angular Signals (Deep Dive)

Store a value

Update UI when value changes

Track dependencies automatically

Signals are reactive state containers

Key Features :

Synchronous state updates

No need for manual subscriptions

Automatic dependency tracking

Basic Example :

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

const count = signal(0);

console.log(count()); // 0

Important:

  • count() → read value
  • Signals behave like functions

Core Concepts of Signals

Signal (Writable Signal)
Stores and updates value

Computed Signal
Derived value from other signals

Effect
Runs when signal changes

Today We Will Focus on Signal

Creating a Signal

Syntax

const name = signal('value');

Usage in component

export class AppComponent {
  username = signal('John');
}

HTML

<p>{{ username() }}</p>

Important:

  • Always use () to access value

Updating Signal Value

Use case:

  • Replace entire value

Using .set()

const count = signal(0);

count.set(5);
console.log(count()); // 5

Updating using .update()

.update() modifies value based on previous value

count.update(value => value + 1);

Example :

increment() {
   this.count.update(v => v + 1);
}

Best for:

  • Increment / decrement

  • Calculated updates

Multiple Update Methods

Different ways :

count.set(10);

count.update(v => v * 2);

count.mutate(v => {
  v.push(100);
});

Use cases:

  • set() → replace
  • update() → compute
  • mutate() → modify arrays/objects

Signals with Arrays & Objects

Using Signals in Template

Signals vs Observables

Summary

5

Ideal for modern Angular applications

4

Cleaner than RxJS for simple cases

3

Automatic UI updates

2

Easy to create and use

1

Signals are modern reactive state management

Quiz

How to read signal value?

A. count

B. count()

C. count.get()

D. value(count)

Quiz

How to read signal value?

A. count

B. count()

C. count.get()

D. value(count)

Quiz-Answer

Which platform is mainly used for professional networking and B2B marketing ?

A. Facebook

B. Instagram

C. LinkedIn

D. Snapchat

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