Angular - Performance Optimization
Which of the following is the correct way to apply a
trackBy function named identify in an Angular template using ngFor?Which of the following is the correct way to apply a trackBy function named identify in an Angular template using ngFor?
easy📝 Syntax Q3 of 15
Step-by-Step Solution
Solution:
Step 1: Syntax of trackBy
The correct syntax usestrackBy: functionNamewithout parentheses.Step 2: Analyze options
*ngFor="let item of items; trackBy: identify"correctly usestrackBy: identify. Options B and D incorrectly usetrackByFn, which is not valid.*ngFor="let item of items; trackBy: identify()"incorrectly calls the function with parentheses.Final Answer:
*ngFor="let item of items; trackBy: identify" -> Option DQuick Check:
trackBy expects a function reference, not a call [OK]
Quick Trick: Use trackBy: functionName without parentheses [OK]
Common Mistakes:
- Using parentheses after the function name
- Using incorrect directive name like trackByFn
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