NativeScript for Mobile App Development Performance and Debugging 2

Question 1

What causes UI jank in NativeScript applications?

Accepted Answer

Running heavy computations synchronously on the main (UI) thread

Answer

Blocking the main thread with CPU-intensive tasks delays UI rendering, causing dropped frames and visible jank.

Question 2

Which NativeScript API runs code in a background thread?

Accepted Answer

Worker API (new Worker())

Answer

NativeScript's Worker API (following the Web Workers spec) creates a true background thread to run CPU-intensive JavaScript without blocking the UI.

Question 3

What is the purpose of tree shaking in a NativeScript webpack build?

Accepted Answer

Remove unused JavaScript code from the bundle to reduce app size

Answer

Tree shaking statically analyzes imports and removes exported code that is never imported or used, reducing the JavaScript bundle size.

Question 4

Which NativeScript ListView optimization recycles view cells to improve scroll performance?

Accepted Answer

Cell/view recycling via the itemTemplates and key template mechanism

Answer

ListView recycles a fixed pool of view cells, reusing them with new data as the user scrolls rather than creating new views for every item.

Question 5

What does the `--clean` flag do when running `ns build`?

Accepted Answer

Deletes the platforms folder and rebuilds native projects from scratch

Answer

`ns build android --clean` deletes the generated Android platform folder and performs a full native rebuild, useful for resolving stale build artifacts.

NativeScript for Mobile App Development Practice Test

NativeScript for Mobile App Development Practice Test

NativeScript for Mobile App Development Performance and Debugging 2