Interview questions in React Native
Expo managed workflow vs bare React Native
Expo gives fast setup, OTA updates, managed builds, and prebuilt APIs; bare gives full native control and arbitrary native modules.
UI unresponsive during large data processing on main thread
Tests RN's dual-thread model and 16.67ms frame budget. Strong answers separate JS and UI thread roles, blame long JS tasks for dropped frames, and propose chunking data to yield the event loop. Red flag: claiming memoization alone solves thread blocking.
Improving React Native startup time
Enable Hermes for fast bytecode startup, shrink and lazy-load the JS bundle via inline requires and RAM bundles, and defer non-critical native init.
Building a native module from scratch
Write a native module class with exported methods or constants, register it via a package, then expose a typed JS wrapper.
Inline styles vs StyleSheet.create
Styles are JS objects passed to the style prop; StyleSheet.create registers styles once for stable references and validation, while inline objects recreate on each render.
View vs Text and nesting rules
View is a flexbox layout container; Text renders and lays out text with inheritance. Text nests inside Text and inherits style; View inside Text is constrained and discouraged.
Default flexDirection and header-content-footer layout
Default flexDirection is column, unlike web's row; give the root flex 1, fixed heights to header and footer, and flex 1 to a scrollable middle.
alignItems vs justifyContent in flexbox
JustifyContent aligns along the main axis, alignItems aligns along the cross axis; with column direction main is vertical and cross is horizontal.
Using position absolute in React Native
Absolute removes a view from flex flow and positions it relative to its nearest positioned ancestor using top, left, right, bottom; ideal for overlays and badges.
Circular View with centered text
Set equal width and height, borderRadius to half that, then justifyContent and alignItems center to place the Text in the middle.
Why Text inherits styles but View does not
Nested Text inherits text styles because it maps to platform attributed-text rendering, while Views are independent layout boxes with no style cascade.
How StyleSheet.create reduces styling overhead
StyleSheet styles are created once with stable references, so identical renders skip reallocation and reduce diffing and serialization work; inline literals allocate new objects each render…
Controlled TextInput with value and onChangeText
Store input text in state, bind value to that state, and update state in onChangeText so React is the single source of truth.
Button vs TouchableOpacity vs Pressable
Button is minimal and platform-styled with limited customization; TouchableOpacity wraps children with an opacity fade; Pressable is the modern, flexible primitive exposing rich press states.
Single useState object for multi-input forms
Hold all fields in one state object, use a generic handler keyed by field name, and update immutably by spreading previous state.
Gesture Responder System lifecycle
A single view becomes the responder for a touch; onStartShouldSetResponder claims it at touch start, onMoveShouldSetResponder claims it on movement, then grant, move, and release callbacks fire.
keyboardShouldPersistTaps in ScrollView
KeyboardShouldPersistTaps controls whether taps dismiss the keyboard or reach children; values never, always, and handled.
Gesture Handler and Reanimated on the UI thread
Gesture Handler tracks gestures natively and Reanimated runs worklets on the UI thread, so animations driven by shared values continue smoothly even when the JS thread is blocked.
navigate vs push in a Stack Navigator
Navigate goes to an existing instance of the route if present, otherwise pushes; push always adds a new instance onto the stack. Use push to revisit the same screen with new params.
Stack Navigator vs Tab Navigator and nesting
A Stack pushes and pops screens for hierarchical drill-down; a Tab switches between parallel top-level sections. Nesting a Stack in each tab gives each tab its own independent push/pop history.
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