Interview practice

Mobile Developer (React Native)

2–5 years · Mid — React Native · JavaScript · Native modules · Offline storage · App release · Performance

scenario Component design 1 of 6

You need to implement a new feature that requires significant changes to the component structure. How do you approach this while ensuring minimal disruption?

What a strong answer covers

Maps out the current component hierarchy and identifies dependencies; designs a modular approach for new components; plans for gradual integration with existing components; writes tests for both old and new components to ensure functionality; communicates changes to the team.

The follow-up you would get

If you encounter resistance from team members regarding the component changes, how would you handle that?

Could you have answered that?

technical Debugging 2 of 6

A user reports that the app crashes intermittently in production without any visible error. What methodical approach do you take to diagnose and fix the issue?

What a strong answer covers

Enables logging and error tracking in the app; reproduces the issue on a local environment with similar data; checks for third-party library updates; reviews the last changes made before the issue surfaced; isolates problematic components for further testing.

The follow-up you would get

If logs don’t provide enough information, what additional tools can you employ?

Could you have answered that?

technical Native Modules 3 of 6

You need to access a device's camera functionality through a native module in React Native. What steps do you follow to implement this feature?

What a strong answer covers

Creates a new native module in Android/iOS; exposes the camera API using React Native's bridge; handles permissions accurately in both platforms; tests the module in various scenarios to ensure reliability; documents the module for future developers.

The follow-up you would get

What challenges might you face when bridging native code with JavaScript?

Could you have answered that?

scenario Ownership 4 of 6

You are responsible for a feature that has just been launched but feedback indicates it doesn't meet user expectations. What actions do you take to address this?

What a strong answer covers

Collects user feedback through analytics and direct user testing; prioritises issues based on severity and frequency; drafts a plan for immediate fixes and longer-term improvements; coordinates with design for UI adjustments; schedules a follow-up release to address feedback.

The follow-up you would get

If the feature was built under tight deadlines, how would you prevent similar situations in future sprints?

Could you have answered that?

technical App Release 5 of 6

You’re preparing to release a new version of your mobile app on both iOS and Android. What key steps do you follow during the release process?

What a strong answer covers

Updates the version number and build identifier in the configuration; runs thorough regression tests on both platforms; checks compliance with app store guidelines; prepares app store screenshots and promotional material; sets up monitoring for crashes after release.

The follow-up you would get

What strategies do you use to handle potential crashes post-release?

Could you have answered that?

scenario Performance 6 of 6

The app's launch time has increased significantly in the latest build, and users are complaining. What steps do you take initially to diagnose the issue?

What a strong answer covers

Profiles the app's startup time using performance tools; checks for heavy imports or synchronous calls in the launch sequence; evaluates the size of assets and resources being loaded; examines the initial state management; considers using code splitting or lazy loading.

The follow-up you would get

If you identify a large asset causing the delay, how would you go about optimising it without sacrificing quality?

Could you have answered that?

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