[Solved] Why does this Angular component code cause a runtime error?export class DemoComponent { @Input() count = 0; countSignal = signal(this.count); } | Angular

Angular - Signals

Why does this Angular component code cause a runtime error?

export class DemoComponent {
  @Input() count = 0;
  countSignal = signal(this.count);
}

AInput properties are not initialized when signals are created

Bsignal() cannot accept numbers as initial values

CcountSignal should be decorated with @Input()

DSignals must be declared inside constructor

Step-by-Step Solution

Solution:

Step 1: Understand input initialization timing
@Input() properties are set after component construction, so this.count is 0 initially but may change later.
Step 2: Problem with signal initialization
Initializing countSignal with this.count captures only initial value, not updates from parent.
Final Answer:
Input properties are not initialized when signals are created -> Option A
Quick Check:
Input values arrive after construction, signals need update logic [OK]

Quick Trick: Input values arrive after construction; signals need update logic [OK]

Common Mistakes:

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Why does this Angular component code cause a runtime error?