Ace the Angular Interview 2025 – Code Your Way to Success!

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What function do track by functions serve in ngFor?

They improve the visual styling of items

They help identify and track items to optimize rendering

Track by functions in ngFor serve the critical purpose of helping the framework optimize rendering by uniquely identifying and tracking items in a rendered list. When using ngFor to repeat items in a template, Angular needs a way to determine if the items have changed, been added, or removed.

By specifying a track by function, you enable Angular to keep track of elements based on a specific property, such as an item's unique identifier. This helps the framework efficiently manage the DOM, ensuring that only the necessary elements are re-rendered when the underlying data changes, minimizing performance overhead.

This is particularly important in scenarios where you have large lists, as it can lead to significant performance improvements by preventing unnecessary DOM manipulations. Overall, the use of track by functions is a best practice in Angular when working with ngFor, helping maintain a smooth and efficient user experience.

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They convert items into observable streams

They sort items in ascending order

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