[Solved] Why might ngOnChanges not be called even though an input property value appears to have changed? — Ans: Because the input value changed internally but its reference stayed the same | Angular

Angular - Lifecycle Hooks

Why might ngOnChanges not be called even though an input property value appears to have changed?

ABecause <code>ngOnChanges</code> only runs once per component lifecycle

BBecause the input value changed internally but its reference stayed the same

CBecause the input property is not decorated with <code>@Input()</code>

DBecause the component does not implement <code>OnInit</code>

Step-by-Step Solution

Solution:

Step 1: Recall how Angular detects input changes
Angular uses reference checks, so internal mutations without reference change do not trigger ngOnChanges.
Step 2: Understand other options
ngOnChanges runs multiple times, @Input is required but assumed here, and OnInit is unrelated.
Final Answer:
Because the input value changed internally but its reference stayed the same -> Option B
Quick Check:
Reference change triggers ngOnChanges [OK]

Quick Trick: Input reference must change to trigger ngOnChanges [OK]

Common Mistakes:

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Why might ngOnChanges not be called even though an input property value appears to have changed?