Technical Interview Preparation: Frontend FocusFebruary 28, 2024

Technical Interview Preparation: Frontend Focus

Complete guide to acing frontend technical interviews. This comprehensive guide covers JavaScript fundamentals, React concepts, algorithm questions, system design basics, and hands-on coding challenges with real examples and solutions.

Interview Overview
JavaScript Fundamentals
React & Framework Questions
HTML & CSS
Algorithm & Data Structures
System Design for Frontend
Coding Challenges
Behavioral Questions
Interview Tips
Mock Interview Questions

Interview Overview {#overview}

Frontend technical interviews typically consist of several components:

Interview Stages

Phone/Video Screening (30-45 mins)
- Basic technical questions
- Coding problem (easy level)
- Cultural fit assessment
Technical Round 1 (45-60 mins)
- JavaScript fundamentals
- DOM manipulation
- Framework-specific questions
Technical Round 2 (45-60 mins)
- Algorithm/Data structure problems
- Code optimization
- Problem-solving approach
System Design (45-60 mins)
- Frontend architecture
- Performance considerations
- Scalability discussions
Final Round (30-45 mins)
- Behavioral questions
- Team fit assessment
- Questions about the role

What Interviewers Look For

Problem-solving skills: How you approach and break down problems
Code quality: Clean, readable, and maintainable code
Communication: Explaining your thought process clearly
Technical depth: Understanding of core concepts
Learning ability: How you handle new or unfamiliar problems

JavaScript Fundamentals {#javascript-fundamentals}

Core Concepts You Must Know

1. Closures

// Common closure question
function createCounter() {
  let count = 0;
  return function() {
    return ++count;
  };
}

const counter = createCounter();
console.log(counter()); // 1
console.log(counter()); // 2

// Interview question: Fix this loop
for (var i = 0; i < 3; i++) {
  setTimeout(() => console.log(i), 100); // Prints 3, 3, 3
}

// Solution 1: Use let
for (let i = 0; i < 3; i++) {
  setTimeout(() => console.log(i), 100); // Prints 0, 1, 2
}

// Solution 2: Use closure
for (var i = 0; i < 3; i++) {
  (function(j) {
    setTimeout(() => console.log(j), 100);
  })(i);
}

2. Hoisting

// What will this code output?
console.log(a); // undefined (not ReferenceError)
console.log(b); // ReferenceError: Cannot access 'b' before initialization
console.log(c); // ReferenceError: c is not defined

var a = 1;
let b = 2;

// Function hoisting
sayHello(); // "Hello!" - works due to hoisting

function sayHello() {
  console.log("Hello!");
}

// But this won't work:
sayGoodbye(); // TypeError: sayGoodbye is not a function

var sayGoodbye = function() {
  console.log("Goodbye!");
};

3. Event Loop & Asynchronous Programming

// Interview question: What's the output order?
console.log('1');

setTimeout(() => console.log('2'), 0);

Promise.resolve().then(() => console.log('3'));

console.log('4');

// Output: 1, 4, 3, 2
// Explanation: Synchronous code first, then microtasks (Promises), then macrotasks (setTimeout)

// Async/Await patterns
async function fetchUserData(id) {
  try {
    const response = await fetch(`/api/users/${id}`);
    if (!response.ok) {
      throw new Error('User not found');
    }
    return await response.json();
  } catch (error) {
    console.error('Error fetching user:', error);
    throw error;
  }
}

// Error handling with Promise.all
async function fetchMultipleUsers(ids) {
  try {
    const users = await Promise.all(
      ids.map(id => fetchUserData(id))
    );
    return users;
  } catch (error) {
    // If any request fails, this will catch it
    console.error('One or more requests failed:', error);
  }
}

4. This Context

const obj = {
  name: 'John',
  greet: function() {
    console.log(`Hello, ${this.name}`);
  },
  greetArrow: () => {
    console.log(`Hello, ${this.name}`); // 'this' refers to global object
  }
};

obj.greet(); // "Hello, John"
obj.greetArrow(); // "Hello, undefined"

// Call, Apply, Bind
function introduce(age, city) {
  console.log(`Hi, I'm ${this.name}, ${age} years old from ${city}`);
}

const person = { name: 'Alice' };

introduce.call(person, 25, 'NYC'); // Hi, I'm Alice, 25 years old from NYC
introduce.apply(person, [25, 'NYC']); // Same as above
const boundIntroduce = introduce.bind(person, 25);
boundIntroduce('NYC'); // Hi, I'm Alice, 25 years old from NYC

5. Prototypes and Inheritance

// Prototype chain
function Person(name) {
  this.name = name;
}

Person.prototype.greet = function() {
  return `Hello, I'm ${this.name}`;
};

function Developer(name, language) {
  Person.call(this, name);
  this.language = language;
}

// Set up inheritance
Developer.prototype = Object.create(Person.prototype);
Developer.prototype.constructor = Developer;

Developer.prototype.code = function() {
  return `${this.name} codes in ${this.language}`;
};

const dev = new Developer('John', 'JavaScript');
console.log(dev.greet()); // "Hello, I'm John"
console.log(dev.code()); // "John codes in JavaScript"

// ES6 Classes (syntactic sugar)
class PersonES6 {
  constructor(name) {
    this.name = name;
  }
  
  greet() {
    return `Hello, I'm ${this.name}`;
  }
}

class DeveloperES6 extends PersonES6 {
  constructor(name, language) {
    super(name);
    this.language = language;
  }
  
  code() {
    return `${this.name} codes in ${this.language}`;
  }
}

React & Framework Questions {#react-framework}

Essential React Concepts

1. Component Lifecycle & Hooks

// Common interview question: Implement a custom hook for data fetching
function useFetch(url) {
  const [data, setData] = useState(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);

  useEffect(() => {
    const abortController = new AbortController();
    
    async function fetchData() {
      try {
        setLoading(true);
        const response = await fetch(url, {
          signal: abortController.signal
        });
        
        if (!response.ok) {
          throw new Error(`HTTP error! status: ${response.status}`);
        }
        
        const result = await response.json();
        setData(result);
      } catch (err) {
        if (err.name !== 'AbortError') {
          setError(err.message);
        }
      } finally {
        setLoading(false);
      }
    }

    fetchData();

    return () => abortController.abort();
  }, [url]);

  return { data, loading, error };
}

// Usage
function UserProfile({ userId }) {
  const { data: user, loading, error } = useFetch(`/api/users/${userId}`);

  if (loading) return <div>Loading...</div>;
  if (error) return <div>Error: {error}</div>;
  if (!user) return <div>User not found</div>;

  return (
    <div>
      <h2>{user.name}</h2>
      <p>{user.email}</p>
    </div>
  );
}

2. State Management

// Interview question: Implement a todo app with useReducer
const todoReducer = (state, action) => {
  switch (action.type) {
    case 'ADD_TODO':
      return {
        ...state,
        todos: [
          ...state.todos,
          {
            id: Date.now(),
            text: action.payload,
            completed: false
          }
        ]
      };
    case 'TOGGLE_TODO':
      return {
        ...state,
        todos: state.todos.map(todo =>
          todo.id === action.payload
            ? { ...todo, completed: !todo.completed }
            : todo
        )
      };
    case 'DELETE_TODO':
      return {
        ...state,
        todos: state.todos.filter(todo => todo.id !== action.payload)
      };
    default:
      return state;
  }
};

function TodoApp() {
  const [state, dispatch] = useReducer(todoReducer, { todos: [] });
  const [input, setInput] = useState('');

  const addTodo = () => {
    if (input.trim()) {
      dispatch({ type: 'ADD_TODO', payload: input });
      setInput('');
    }
  };

  return (
    <div>
      <input
        value={input}
        onChange={(e) => setInput(e.target.value)}
        onKeyPress={(e) => e.key === 'Enter' && addTodo()}
      />
      <button onClick={addTodo}>Add</button>
      
      <ul>
        {state.todos.map(todo => (
          <li key={todo.id}>
            <span
              style={{ 
                textDecoration: todo.completed ? 'line-through' : 'none' 
              }}
              onClick={() => dispatch({ type: 'TOGGLE_TODO', payload: todo.id })}
            >
              {todo.text}
            </span>
            <button 
              onClick={() => dispatch({ type: 'DELETE_TODO', payload: todo.id })}
            >
              Delete
            </button>
          </li>
        ))}
      </ul>
    </div>
  );
}

3. Performance Optimization

// Interview question: Optimize this component
import React, { useState, useMemo, useCallback, memo } from 'react';

// Child component that should only re-render when props change
const TodoItem = memo(({ todo, onToggle, onDelete }) => {
  console.log('Rendering TodoItem:', todo.text);
  
  return (
    <li>
      <span
        style={{ textDecoration: todo.completed ? 'line-through' : 'none' }}
        onClick={() => onToggle(todo.id)}
      >
        {todo.text}
      </span>
      <button onClick={() => onDelete(todo.id)}>Delete</button>
    </li>
  );
});

function OptimizedTodoApp() {
  const [todos, setTodos] = useState([]);
  const [filter, setFilter] = useState('all');
  const [input, setInput] = useState('');

  // Memoize filtered todos
  const filteredTodos = useMemo(() => {
    return todos.filter(todo => {
      if (filter === 'active') return !todo.completed;
      if (filter === 'completed') return todo.completed;
      return true;
    });
  }, [todos, filter]);

  // Memoize callbacks to prevent unnecessary re-renders
  const handleToggle = useCallback((id) => {
    setTodos(prevTodos =>
      prevTodos.map(todo =>
        todo.id === id ? { ...todo, completed: !todo.completed } : todo
      )
    );
  }, []);

  const handleDelete = useCallback((id) => {
    setTodos(prevTodos => prevTodos.filter(todo => todo.id !== id));
  }, []);

  const addTodo = useCallback(() => {
    if (input.trim()) {
      setTodos(prevTodos => [
        ...prevTodos,
        { id: Date.now(), text: input, completed: false }
      ]);
      setInput('');
    }
  }, [input]);

  return (
    <div>
      <input
        value={input}
        onChange={(e) => setInput(e.target.value)}
        onKeyPress={(e) => e.key === 'Enter' && addTodo()}
      />
      <button onClick={addTodo}>Add Todo</button>
      
      <div>
        <button onClick={() => setFilter('all')}>All</button>
        <button onClick={() => setFilter('active')}>Active</button>
        <button onClick={() => setFilter('completed')}>Completed</button>
      </div>

      <ul>
        {filteredTodos.map(todo => (
          <TodoItem
            key={todo.id}
            todo={todo}
            onToggle={handleToggle}
            onDelete={handleDelete}
          />
        ))}
      </ul>
    </div>
  );
}

HTML & CSS {#html-css}

Common HTML/CSS Interview Questions

1. CSS Specificity and Box Model

/* Specificity calculation */
#header .nav ul li a { /* specificity: 0,1,1,3 */
  color: blue;
}

.nav a { /* specificity: 0,0,1,1 */
  color: red;
}

/* The first rule wins due to higher specificity */

/* Box model */
.box {
  width: 300px;
  padding: 20px;
  border: 5px solid black;
  margin: 10px;
  box-sizing: border-box; /* Total width = 300px */
  /* Without box-sizing: border-box, total width = 350px */
}

2. Flexbox and Grid

/* Flexbox interview question: Center content */
.flex-container {
  display: flex;
  justify-content: center; /* horizontal centering */
  align-items: center; /* vertical centering */
  height: 100vh;
}

/* Grid layout */
.grid-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1rem;
  padding: 1rem;
}

/* Responsive grid */
.responsive-grid {
  display: grid;
  grid-template-columns: 1fr;
}

@media (min-width: 768px) {
  .responsive-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (min-width: 1024px) {
  .responsive-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

3. CSS Position and Z-index

/* Position interview scenarios */
.parent {
  position: relative;
  width: 400px;
  height: 300px;
}

.child-absolute {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%); /* Perfect centering */
}

.sticky-header {
  position: sticky;
  top: 0;
  background: white;
  z-index: 100;
}

/* Z-index stacking context */
.modal-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  z-index: 1000;
}

.modal {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: white;
  z-index: 1001;
}

Algorithm & Data Structures {#algorithms}

Common Frontend Algorithm Questions

1. Array Manipulation

// Question: Remove duplicates from array
function removeDuplicates(arr) {
  // Method 1: Using Set
  return [...new Set(arr)];
  
  // Method 2: Using filter and indexOf
  return arr.filter((item, index) => arr.indexOf(item) === index);
  
  // Method 3: Using reduce
  return arr.reduce((unique, item) => {
    return unique.includes(item) ? unique : [...unique, item];
  }, []);
}

// Question: Find the intersection of two arrays
function intersection(arr1, arr2) {
  const set1 = new Set(arr1);
  return arr2.filter(item => set1.has(item));
}

// Question: Flatten nested array
function flattenArray(arr) {
  // Method 1: Using built-in flat()
  return arr.flat(Infinity);
  
  // Method 2: Recursive approach
  function flatten(arr) {
    const result = [];
    for (let item of arr) {
      if (Array.isArray(item)) {
        result.push(...flatten(item));
      } else {
        result.push(item);
      }
    }
    return result;
  }
  return flatten(arr);
}

2. String Manipulation

// Question: Check if string is a palindrome
function isPalindrome(str) {
  const cleaned = str.toLowerCase().replace(/[^a-z0-9]/g, '');
  return cleaned === cleaned.split('').reverse().join('');
}

// Question: Find longest substring without repeating characters
function longestUniqueSubstring(str) {
  let maxLength = 0;
  let start = 0;
  const seen = new Map();
  
  for (let end = 0; end < str.length; end++) {
    const char = str[end];
    
    if (seen.has(char) && seen.get(char) >= start) {
      start = seen.get(char) + 1;
    }
    
    seen.set(char, end);
    maxLength = Math.max(maxLength, end - start + 1);
  }
  
  return maxLength;
}

// Question: Implement debounce
function debounce(func, delay) {
  let timeoutId;
  
  return function(...args) {
    clearTimeout(timeoutId);
    timeoutId = setTimeout(() => func.apply(this, args), delay);
  };
}

// Usage
const debouncedSearch = debounce((query) => {
  console.log('Searching for:', query);
}, 300);

3. Object and Array Operations

// Question: Deep clone an object
function deepClone(obj) {
  if (obj === null || typeof obj !== 'object') {
    return obj;
  }
  
  if (obj instanceof Date) {
    return new Date(obj.getTime());
  }
  
  if (obj instanceof Array) {
    return obj.map(item => deepClone(item));
  }
  
  if (typeof obj === 'object') {
    const cloned = {};
    for (let key in obj) {
      if (obj.hasOwnProperty(key)) {
        cloned[key] = deepClone(obj[key]);
      }
    }
    return cloned;
  }
}

// Question: Group array of objects by property
function groupBy(array, key) {
  return array.reduce((groups, item) => {
    const value = item[key];
    if (!groups[value]) {
      groups[value] = [];
    }
    groups[value].push(item);
    return groups;
  }, {});
}

// Usage
const users = [
  { name: 'John', department: 'Engineering' },
  { name: 'Jane', department: 'Marketing' },
  { name: 'Bob', department: 'Engineering' }
];

const groupedUsers = groupBy(users, 'department');

System Design for Frontend {#system-design}

Key Topics for Frontend System Design

1. Component Architecture

Question: Design a reusable Modal component

Considerations:
- Portal rendering (render outside parent DOM)
- Focus management
- Keyboard accessibility (ESC key)
- Background scroll prevention
- Animation/transitions
- Multiple modal stacking

Implementation approach:

// Modal System Design
import ReactDOM from 'react-dom';
import { useEffect, useRef } from 'react';

function Modal({ isOpen, onClose, children, className }) {
  const modalRef = useRef(null);
  const previousActiveElement = useRef(null);

  useEffect(() => {
    if (isOpen) {
      // Store currently focused element
      previousActiveElement.current = document.activeElement;
      
      // Prevent body scroll
      document.body.style.overflow = 'hidden';
      
      // Focus modal
      modalRef.current?.focus();
    }

    return () => {
      // Restore body scroll
      document.body.style.overflow = 'unset';
      
      // Restore focus
      if (previousActiveElement.current) {
        previousActiveElement.current.focus();
      }
    };
  }, [isOpen]);

  useEffect(() => {
    const handleEscape = (e) => {
      if (e.key === 'Escape') {
        onClose();
      }
    };

    if (isOpen) {
      document.addEventListener('keydown', handleEscape);
    }

    return () => {
      document.removeEventListener('keydown', handleEscape);
    };
  }, [isOpen, onClose]);

  if (!isOpen) return null;

  return ReactDOM.createPortal(
    <div 
      className="modal-backdrop"
      onClick={(e) => {
        if (e.target === e.currentTarget) {
          onClose();
        }
      }}
    >
      <div
        ref={modalRef}
        className={`modal ${className || ''}`}
        role="dialog"
        aria-modal="true"
        tabIndex={-1}
      >
        <button
          className="modal-close"
          onClick={onClose}
          aria-label="Close modal"
        >
          ×
        </button>
        {children}
      </div>
    </div>,
    document.body
  );
}

2. State Management Architecture

Question: Design state management for a large e-commerce application

Consider:
- User authentication state
- Shopping cart state
- Product catalog state
- UI state (modals, notifications)
- Caching strategy
- Optimistic updates

Architecture approach:
- Context API for global state
- Custom hooks for business logic
- React Query for server state
- Local state for component-specific data

// State Management Design
const AppContext = createContext();

function AppProvider({ children }) {
  // Authentication state
  const [user, setUser] = useState(null);
  
  // Shopping cart state
  const [cart, setCart] = useState([]);
  
  // UI state
  const [notifications, setNotifications] = useState([]);

  const addToCart = useCallback((product) => {
    setCart(prevCart => {
      const existingItem = prevCart.find(item => item.id === product.id);
      if (existingItem) {
        return prevCart.map(item =>
          item.id === product.id
            ? { ...item, quantity: item.quantity + 1 }
            : item
        );
      }
      return [...prevCart, { ...product, quantity: 1 }];
    });
  }, []);

  const value = {
    user,
    setUser,
    cart,
    addToCart,
    notifications,
    setNotifications
  };

  return (
    <AppContext.Provider value={value}>
      {children}
    </AppContext.Provider>
  );
}

// Custom hooks for different domains
function useAuth() {
  const { user, setUser } = useContext(AppContext);
  
  const login = async (credentials) => {
    try {
      const response = await authAPI.login(credentials);
      setUser(response.user);
      return response;
    } catch (error) {
      throw error;
    }
  };

  const logout = async () => {
    await authAPI.logout();
    setUser(null);
  };

  return { user, login, logout };
}

function useCart() {
  const { cart, addToCart } = useContext(AppContext);
  
  const removeFromCart = useCallback((productId) => {
    setCart(prevCart => prevCart.filter(item => item.id !== productId));
  }, []);

  const getTotalPrice = useMemo(() => {
    return cart.reduce((total, item) => total + item.price * item.quantity, 0);
  }, [cart]);

  return {
    cart,
    addToCart,
    removeFromCart,
    totalPrice: getTotalPrice
  };
}

3. Performance Optimization Strategy

Question: How would you optimize a large data table component?

Considerations:
- Virtual scrolling for large datasets
- Memoization of expensive calculations
- Debounced search/filtering
- Pagination vs infinite scroll
- Column sorting and filtering
- Export functionality

Key techniques:
1. React.memo for preventing unnecessary re-renders
2. useMemo for expensive calculations
3. useCallback for stable function references
4. Code splitting for reducing bundle size
5. Lazy loading for images and components
6. Service workers for caching

Coding Challenges {#coding-challenges}

Live Coding Exercises

1. Build a Search Component

// Question: Build a search component with debouncing and suggestions

function SearchComponent({ onSearch, getSuggestions }) {
  const [query, setQuery] = useState('');
  const [suggestions, setSuggestions] = useState([]);
  const [showSuggestions, setShowSuggestions] = useState(false);
  const [loading, setLoading] = useState(false);

  // Debounce search queries
  const debouncedQuery = useDebounce(query, 300);

  useEffect(() => {
    if (debouncedQuery) {
      setLoading(true);
      getSuggestions(debouncedQuery)
        .then(results => {
          setSuggestions(results);
          setShowSuggestions(true);
        })
        .catch(console.error)
        .finally(() => setLoading(false));
    } else {
      setSuggestions([]);
      setShowSuggestions(false);
    }
  }, [debouncedQuery, getSuggestions]);

  const handleSubmit = (e) => {
    e.preventDefault();
    if (query.trim()) {
      onSearch(query);
      setShowSuggestions(false);
    }
  };

  const handleSuggestionClick = (suggestion) => {
    setQuery(suggestion);
    onSearch(suggestion);
    setShowSuggestions(false);
  };

  return (
    <div className="search-container">
      <form onSubmit={handleSubmit}>
        <input
          type="text"
          value={query}
          onChange={(e) => setQuery(e.target.value)}
          placeholder="Search..."
          onFocus={() => suggestions.length > 0 && setShowSuggestions(true)}
          onBlur={() => setTimeout(() => setShowSuggestions(false), 150)}
        />
        <button type="submit" disabled={!query.trim()}>
          Search
        </button>
      </form>

      {showSuggestions && (
        <div className="suggestions">
          {loading ? (
            <div>Loading...</div>
          ) : (
            suggestions.map((suggestion, index) => (
              <div
                key={index}
                className="suggestion-item"
                onClick={() => handleSuggestionClick(suggestion)}
              >
                {suggestion}
              </div>
            ))
          )}
        </div>
      )}
    </div>
  );
}

function useDebounce(value, delay) {
  const [debouncedValue, setDebouncedValue] = useState(value);

  useEffect(() => {
    const handler = setTimeout(() => setDebouncedValue(value), delay);
    return () => clearTimeout(handler);
  }, [value, delay]);

  return debouncedValue;
}

2. Implement Infinite Scroll

// Question: Implement infinite scroll with loading states

function InfiniteScrollList({ fetchData, renderItem }) {
  const [items, setItems] = useState([]);
  const [loading, setLoading] = useState(false);
  const [hasMore, setHasMore] = useState(true);
  const [page, setPage] = useState(1);

  const observer = useRef();
  const lastItemRef = useCallback(node => {
    if (loading) return;
    if (observer.current) observer.current.disconnect();
    
    observer.current = new IntersectionObserver(entries => {
      if (entries[0].isIntersecting && hasMore) {
        setPage(prevPage => prevPage + 1);
      }
    });
    
    if (node) observer.current.observe(node);
  }, [loading, hasMore]);

  useEffect(() => {
    setLoading(true);
    
    fetchData(page)
      .then(response => {
        setItems(prevItems => [...prevItems, ...response.data]);
        setHasMore(response.hasMore);
      })
      .catch(console.error)
      .finally(() => setLoading(false));
  }, [page, fetchData]);

  return (
    <div className="infinite-scroll-container">
      {items.map((item, index) => {
        const isLast = index === items.length - 1;
        return (
          <div
            key={item.id}
            ref={isLast ? lastItemRef : null}
            className="list-item"
          >
            {renderItem(item)}
          </div>
        );
      })}
      
      {loading && (
        <div className="loading-indicator">
          Loading more items...
        </div>
      )}
      
      {!hasMore && items.length > 0 && (
        <div className="end-message">
          No more items to load
        </div>
      )}
    </div>
  );
}

// Usage
function App() {
  const fetchPosts = async (page) => {
    const response = await fetch(`/api/posts?page=${page}&limit=10`);
    return response.json();
  };

  const renderPost = (post) => (
    <div>
      <h3>{post.title}</h3>
      <p>{post.excerpt}</p>
    </div>
  );

  return (
    <InfiniteScrollList
      fetchData={fetchPosts}
      renderItem={renderPost}
    />
  );
}

Behavioral Questions {#behavioral}

Common Behavioral Questions for Frontend Engineers

1. Technical Leadership

Question: "Tell me about a time you had to make a technical decision that impacted the team."

STAR Framework Answer:

Situation: Our team was building a new e-commerce platform and needed to choose between Vue 2 and React for the frontend.
Task: As the senior frontend engineer, I needed to evaluate both options and make a recommendation.
Action: I created a comparison matrix evaluating factors like team expertise, community support, performance, and long-term maintenance. I built prototypes in both frameworks and presented findings to the team.
Result: We chose React based on better TypeScript support and team familiarity. The decision led to faster development and easier onboarding of new team members.

2. Problem Solving

Question: "Describe a challenging bug you encountered and how you solved it."

Example Answer:

Situation: Users reported that our application was randomly freezing in production, but we couldn't reproduce it locally.
Task: Identify the root cause and implement a fix without affecting user experience.
Action: I implemented comprehensive logging and error tracking with Sentry, added performance monitoring, and discovered it was a memory leak in a third-party chart library during rapid data updates.
Result: Fixed the issue by implementing proper cleanup in useEffect and upgrading the library. Reduced user-reported freezing issues by 95%.

3. Collaboration

Question: "Tell me about a time you disagreed with a design decision."