Mobile Developer 路 Intern to senior
React Native interviews reuse most of React: components, hooks, state and rendering performance. This collection covers those shared foundations; platform-specific Android and iOS questions will be added over time.
59 questions
The virtual DOM is a lightweight JavaScript copy of the UI that React compares with the previous version after each update, so it only changes the parts of the real DOM that actually differ.
Props are read-only inputs passed from a parent component, while state is data a component owns and can change over time, which triggers a re-render when updated.
TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. It catches type errors in the editor and at build time, and it documents the shape of data for the next person who reads the code.
Both describe object shapes. interface can be merged and is preferred for public object contracts; type can express unions, intersections and primitives, and cannot be reopened later.
Git is a distributed version control system that tracks changes to files on your machine; GitHub is a hosting service for Git repositories that adds collaboration features such as pull requests, code review and CI.
git fetch downloads new commits from the remote without changing your working branch; git pull runs a fetch and then merges (or rebases) those commits into your current branch.
Give a 60-90 second summary in three parts: what you do now, one or two achievements that show your strengths, and why this role is the logical next step.
Connect two or three of your strongest, provable skills directly to the needs in the job description, give a short piece of evidence for each, and show genuine interest in the team鈥檚 work.
Give specific evidence of deliberate learning through projects, feedback, reading, experimentation or mentoring rather than listing technologies.
Connect something specific about the company, product, engineering challenges or team to your own experience and career goals.
Hooks are functions such as useState and useEffect that let function components use state, lifecycle behaviour and other React features; they must be called at the top level of a component or custom hook, never inside loops, conditions or nested functions.
Keys give each list item a stable identity so React can match items between renders and correctly add, remove or reorder them without recreating or mixing up their state.
useEffect runs a function after the component renders; the dependency array tells React when to re-run it: with no array it runs after every render, with an empty array only after the first, and with values only when those values change.
A controlled component keeps the input's value in React state and updates it through onChange, while an uncontrolled component lets the DOM hold the value and you read it with a ref when needed.
Prop drilling is passing props through several layers of components that do not use them just to reach a deeply nested child; you avoid it with composition, the Context API or a state management library.
any turns off checking. unknown is a type-safe any: you must narrow it before use. never means a value cannot exist, used for exhaustive checks and functions that always throw.
Generics are type parameters: they let a function, class or type work with many types while keeping the relationship between inputs and outputs, instead of falling back to any.
A union (A | B) is a value that is one of the members. An intersection (A & B) is a value that must satisfy both types at once.
Utility types are built-in helpers that transform an existing type: Partial makes every field optional, Required the opposite, Pick keeps a set of keys, Omit removes them, and Record builds a key/value map.
Both integrate changes from one branch into another: merge keeps both histories and joins them with a merge commit, while rebase rewrites your commits so they appear on top of the target branch, giving a linear history.