Why is it wrong to mutate an array inside a signal like this? items = signal ([]); add(x: string) { this.items().push(x); }

The signal reference doesn't change, so Angular isn't notified; use update(list => [...list, x])

push throws an error inside signals

Angular · Junior · Question 39 of 75

Why is it wrong to mutate an array inside a signal like this?

items = signal<string[]>([]);
add(x: string) { this.items().push(x); }

✓Correct answer: The signal reference doesn't change, so Angular isn't notified; use update(list => [...list, x])
2Signals can't contain arrays
3push throws an error inside signals

Explanation

Signals compare values with Object.is by default. Mutating the same array keeps the reference, so dependents are not notified. Create a new array or object instead.

Why is it wrong to mutate an array inside a signal like this?

Explanation

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