[Solved] Which of the following is the correct syntax to use trackBy in an ngFor loop? — Ans: *ngFor="let item of items; trackBy: trackByFn" | Angular

Angular - Performance Optimization

Which of the following is the correct syntax to use trackBy in an ngFor loop?

A<code>*ngFor="let item of items; trackByFn"</code>

B<code>*ngFor="let item of items; trackBy: trackByFn"</code>

C<code>*ngFor="let item of items; trackByFn()"</code>

D<code>*ngFor="let item of items; trackBy=trackByFn()"</code>

Step-by-Step Solution

Solution:

Step 1: Recall the correct ngFor syntax with trackBy
The correct syntax uses a semicolon and the keyword trackBy followed by the function name without parentheses.
Step 2: Compare options
*ngFor="let item of items; trackBy: trackByFn" matches the correct syntax: *ngFor="let item of items; trackBy: trackByFn". Others either miss the keyword or use parentheses incorrectly.
Final Answer:
*ngFor="let item of items; trackBy: trackByFn" -> Option B
Quick Check:
Correct syntax includes 'trackBy:' keyword [OK]

Quick Trick: Use 'trackBy:' keyword with function name, no parentheses [OK]

Common Mistakes:

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Which of the following is the correct syntax to use trackBy in an ngFor loop?