[Solved] // Template: {{ items | customPipe }}If customPipe is pure and the array items is mutated by items.push(4) without changing the reference, what will happen? | Angular

Angular - Pipes

Given this Angular pipe usage:

items = [1, 2, 3];
// Template: {{ items | customPipe }}

If customPipe is pure and the array items is mutated by items.push(4) without changing the reference, what will happen?

AThe pipe will run and update the output to include 4.

BAngular throws an error due to mutation.

CThe pipe runs only if change detection is manually triggered.

DThe pipe will not run; output remains unchanged.

Step-by-Step Solution

Solution:

Step 1: Understand pure pipe input change detection
Pure pipes run only when the input reference changes, not when the content inside the object changes.
Step 2: Analyze mutation effect on pipe execution
Mutating the array with push() does not change the reference, so the pure pipe does not run again and output stays the same.
Final Answer:
The pipe will not run; output remains unchanged. -> Option D
Quick Check:
Pure pipe ignores internal mutations = C [OK]

Quick Trick: Pure pipes need new object references to update [OK]

Common Mistakes:

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