React JS MCQ

{ "questions": [ { "question": "React is mainly used for building ____.", "options": ["Database", "User Interface", "Server", "Operating System"], "answer": 1 }, { "question": "React was developed by ____.", "options": ["Google", "Microsoft", "Facebook", "Amazon"], "answer": 2 }, { "question": "In React, components are ____.", "options": ["Reusable UI pieces", "Database tables", "CSS files", "Server functions"], "answer": 0 }, { "question": "JSX stands for ____.", "options": ["Java Syntax Extension", "JavaScript XML", "JSON XML", "JavaScript XHR"], "answer": 1 }, { "question": "Which hook is used for state management in functional components?", "options": ["useFetch", "useState", "useEffect", "useRef"], "answer": 1 }, { "question": "Which hook is used for side effects?", "options": ["useState", "useReducer", "useEffect", "useMemo"], "answer": 2 }, { "question": "Props are ____.", "options": ["Mutable", "Immutable", "Functions only", "Database values"], "answer": 1 }, { "question": "State in React is ____.", "options": ["Immutable", "Mutable", "Static", "External"], "answer": 1 }, { "question": "Virtual DOM improves ____.", "options": ["Security", "Performance", "Storage", "Networking"], "answer": 1 }, { "question": "Which method is used to render React content into DOM?", "options": ["ReactDOM.render()", "React.render()", "DOM.render()", "renderDOM()"], "answer": 0 }, { "question": "Keys in React lists help in ____.", "options": ["Styling", "Identifying elements", "Fetching data", "Routing"], "answer": 1 }, { "question": "Which hook returns a memoized value?", "options": ["useMemo", "useState", "useEffect", "useRef"], "answer": 0 }, { "question": "Which hook is used to persist values across renders without re-render?", "options": ["useRef", "useMemo", "useState", "useEffect"], "answer": 0 }, { "question": "React components must return ____.", "options": ["HTML string", "Single root element", "Array only", "JSON"], "answer": 1 }, { "question": "Which syntax is used to embed JavaScript inside JSX?", "options": ["()", "[]", "{}", "<>"], "answer": 2 }, { "question": "Which lifecycle method runs after component mounts (class component)?", "options": ["componentWillMount", "componentDidMount", "componentUpdate", "componentRender"], "answer": 1 }, { "question": "Which hook replaces lifecycle methods in functional components?", "options": ["useState", "useEffect", "useRef", "useCallback"], "answer": 1 }, { "question": "Controlled components are controlled by ____.", "options": ["DOM", "State", "CSS", "Server"], "answer": 1 }, { "question": "Which tool is commonly used to create React apps quickly?", "options": ["npm start", "create-react-app", "react-cli", "node create"], "answer": 1 }, { "question": "Fragments in React are used to ____.", "options": ["Add styling", "Group elements without extra DOM", "Handle routing", "Fetch data"], "answer": 1 }, { "question": "Which hook memoizes callback functions?", "options": ["useMemo", "useCallback", "useState", "useEffect"], "answer": 1 }, { "question": "React Router is used for ____.", "options": ["Database", "Navigation", "Authentication", "Animation"], "answer": 1 }, { "question": "Which prop is mandatory for list rendering?", "options": ["id", "key", "value", "index"], "answer": 1 }, { "question": "Which hook manages complex state logic?", "options": ["useReducer", "useState", "useEffect", "useRef"], "answer": 0 }, { "question": "React follows ____ data flow.", "options": ["Two-way", "Circular", "One-way", "Random"], "answer": 2 }, { "question": "Portals in React allow rendering into ____.", "options": ["Same component", "Different DOM subtree", "Database", "Server"], "answer": 1 }, { "question": "Context API is used for ____.", "options": ["Global state sharing", "Styling", "Routing", "Testing"], "answer": 0 }, { "question": "Which hook gives access to context?", "options": ["useContext", "useState", "useReducer", "useMemo"], "answer": 0 }, { "question": "Lazy loading components is done using ____.", "options": ["React.lazy", "React.load", "useLazy", "lazyLoad"], "answer": 0 }, { "question": "Suspense is used with lazy loading for ____.", "options": ["Routing", "Fallback UI", "State", "API calls"], "answer": 1 } ] }