interview_challenges.md

Basic JavaScript Challenges:

1. Write a function that adds two numbers.
2. Write a function that subtracts two numbers.
3. Write a function that multiplies two numbers.
4. Write a function that divides two numbers.
5. Write a function that calculates the square of a number.
6. Write a function to find the maximum of two numbers.
7. Write a function to find the minimum of two numbers.
8. Write a function to check if a number is even or odd.
9. Write a function to check if a number is prime.
10. Write a function to find the factorial of a number.

Array Challenges:

11. Write a function to find the sum of all elements in an array.
12. Write a function to find the average of all elements in an array.
13. Write a function to reverse an array.
14. Write a function to check if an array is sorted in ascending order.
15. Write a function to remove duplicates from an array.
16. Write a function to find the intersection of two arrays.
17. Write a function to merge two sorted arrays.
18. Write a function to count the occurrences of an element in an array.
19. Write a function to find the largest and smallest elements in an array.
20. Write a function to rotate an array to the left by a specified number of positions.

String Challenges:

21. Write a function to reverse a string.
22. Write a function to check if a string is a palindrome.
23. Write a function to count the number of vowels in a string.
24. Write a function to find the longest word in a string.
25. Write a function to capitalize the first letter of each word in a string.
26. Write a function to check if two strings are anagrams.
27. Write a function to remove all spaces from a string.
28. Write a function to find the first non-repeated character in a string.
29. Write a function to check if a string contains only numbers.
30. Write a function to count the occurrences of a word in a string.

Object Challenges:

31. Create an object representing a person with name, age, and address properties.
32. Write a function to list all the keys of an object.
33. Write a function to list all the values of an object.
34. Write a function to merge two objects into one.
35. Write a function to check if a key exists in an object.
36. Write a function to remove a key from an object.
37. Write a function to deep clone an object.
38. Write a function to calculate the total age of people in an array of person objects.
39. Write a function to find the youngest person in an array of person objects.
40. Write a function to convert an array of objects into a single object with key-value pairs.

Functional Programming Challenges:

41. Write a function to implement map function.
42. Write a function to implement filter function.
43. Write a function to implement reduce function.
44. Write a function to implement the forEach function.
45. Write a function to implement the some function.
46. Write a function to implement the every function.
47. Write a function to implement a simple debounce function.
48. Write a function to implement a simple throttle function.
49. Write a function to compose two functions.
50. Write a function to curry a function.

Advanced JavaScript Challenges:

51. Implement a promise-based function to make an HTTP GET request.
52. Write a function to implement a simple event emitter.
53. Create a function to flatten a nested array.
54. Write a function to implement memoization for a given function.
55. Create a function to perform deep comparison of two objects.
56. Write a function to find the shortest path in a graph using Dijkstra's algorithm.
57. Create a function to generate a unique identifier (UUID).
58. Write a function to find the common elements in multiple arrays.
59. Create a function to implement a basic Pub/Sub pattern.
60. Write a function to implement a basic routing system for a single-page application.

DOM and Web Development Challenges:

61. Create a simple image carousel using HTML, CSS, and JavaScript.
62. Implement a form validation function to validate email, password, and other inputs.
63. Write a function to fetch data from an API and display it on a web page.
64. Create a responsive navigation menu using CSS and JavaScript.
65. Implement infinite scrolling on a web page using the Intersection Observer API.
66. Create a real-time chat application using WebSockets.
67. Build a simple to-do list application with add, edit, and delete functionalities.
68. Implement a drag-and-drop feature for reordering items on a web page.
69. Create a modal dialog that can be opened and closed with a button click.
70. Implement lazy loading for images on a web page to improve performance.

Testing Challenges:

71. Write unit tests for a simple math library (add, subtract, multiply, divide).
72. Implement tests for a function that reverses an array.
73. Write tests for a function that checks if a string is a palindrome.
74. Create tests for a function that merges two sorted arrays.
75. Implement tests for an API request function using a testing library (e.g., Jest).
76. Write tests for a function that calculates the factorial of a number.
77. Create tests for a function that validates email addresses.
78. Implement tests for a function that counts the number of vowels in a string.
79. Write tests for a function that removes duplicates from an array.
80. Create tests for a function that calculates the average of numbers in an array.

Concurrency and Asynchronous Challenges:

81. Write a function to fetch data from multiple APIs in parallel and combine the results.
82. Implement a simple promise-based task queue for managing concurrent tasks.
83. Create a function to simulate asynchronous file uploads and track progress.
84. Write a function to perform parallel processing of a large array using web workers.
85. Implement a function to synchronize access to a shared resource using semaphores.
86. Write a function to perform asynchronous image loading and display images as they load.
87. Create a function to implement a basic promise-based throttle mechanism.
88. Implement a function to handle race conditions in a concurrent program.
89. Write a function to simulate a producer-consumer problem using asynchronous queues.
90. Create a function to perform parallel computation of a complex task and merge the results.

Security and Performance Challenges:

91. Write a function to sanitize user input to prevent cross-site scripting (XSS) attacks.
92. Implement a function to hash and salt passwords for secure storage.
93. Write a function to prevent SQL injection in database queries.
94. Create a function to optimize the loading of external scripts and resources.
95. Implement a function to secure user authentication using JSON Web Tokens (JWT).
96. Write a function to protect against brute force attacks on login forms.
97. Implement a Content Security Policy (CSP) for a web application.
98. Create a function to prevent clickjacking attacks using X-Frame-Options headers.
99. Implement a function to protect against cross-site request forgery (CSRF) attacks.
100. Write a function to detect and prevent security vulnerabilities in third-party libraries and dependencies.

Advanced Algorithm Challenges:

1. Longest Substring Without Repeating Characters: Write a function to find the longest substring without repeating characters in a given string.

2. Sudoku Solver: Create a program that can solve a Sudoku puzzle.

3. A Pathfinding Algorithm:* Implement the A* pathfinding algorithm to find the shortest path in a grid.

4. Knapsack Problem: Solve the 0/1 Knapsack problem using dynamic programming.

5. Traveling Salesman Problem: Create an algorithm to find the shortest route that visits a set of cities and returns to the starting city.

6. Conway's Game of Life: Implement Conway's Game of Life, a cellular automaton simulation.

7. Optimal Change: Write a function to calculate the optimal way to make change for a given amount of money using the fewest coins.

8. Graph Traversal: Create a function to perform depth-first search (DFS) and breadth-first search (BFS) on a graph.

9. Big Integer Arithmetic: Implement arithmetic operations for big integers (numbers larger than JavaScript's Number type).

10. Heap Implementation: Write a class to create and manipulate a binary heap (min-heap or max-heap).

Advanced Data Structures:

11. Trie Implementation: Create a trie data structure for efficient string search and autocomplete.

12. Bloom Filter: Implement a Bloom filter, a probabilistic data structure for membership testing.

13. Red-Black Tree: Implement a Red-Black Tree and perform insertions, deletions, and searches.

14. LRU Cache: Create an LRU (Least Recently Used) cache with a fixed size.

15. Suffix Tree: Implement a suffix tree, a data structure for efficient substring searches.

16. Skip List: Create a skip list data structure for fast search and insert operations.

17. Fenwick Tree (Binary Indexed Tree): Implement a Fenwick Tree for efficient range sum queries.

18. B-Tree: Create a B-tree data structure and implement insertion, deletion, and search operations.

19. Priority Queue: Implement a priority queue data structure using a binary heap or other techniques.

20. Bloom Filter Set Operations: Extend the Bloom filter to perform set operations (union, intersection, etc.).

Concurrency and Parallelism:

21. Web Workers: Use Web Workers to parallelize a time-consuming task in a web application.

22. Async/Await Parallel Processing: Implement parallel processing of asynchronous tasks using async/await.

23. Shared Memory and Atomics: Create a multi-threaded JavaScript program using shared memory and atomic operations.

24. Race Conditions Handling: Write code to handle and prevent race conditions in a concurrent environment.

25. Parallel MapReduce: Implement a parallel MapReduce framework for distributed processing.

26. Asynchronous Generators: Use asynchronous generators to process a large dataset without loading it all into memory.

27. Task Scheduling: Create a task scheduler that can execute tasks in a specific order or with dependencies.

28. Rate Limiting: Implement a rate-limiting mechanism to control how often a function or API can be called.

29. Parallel Merge Sort: Write a parallel merge sort algorithm to sort large arrays more efficiently.

30. Deadlock Detection: Create a program to detect and handle deadlocks in a concurrent system.

Security Challenges:

31. Cross-Site Scripting (XSS) Challenge: Try to exploit and then protect against XSS vulnerabilities in a web application.

32. SQL Injection Challenge: Attempt to exploit and then secure a vulnerable SQL query in a web application.

33. Secure Session Management: Create a secure session management system with proper session handling, validation, and encryption.

34. JWT Token Security: Test the security of a JSON Web Token (JWT) implementation and implement best practices.

35. CORS Bypass: Try to bypass Cross-Origin Resource Sharing (CORS) restrictions and then secure the application.

36. Password Cracking: Implement a program to crack hashed passwords and then discuss password security best practices.

37. Authentication Bypass: Attempt to bypass authentication mechanisms in a web application and discuss mitigation techniques.

38. Security Headers Implementation: Configure and test various security headers, such as Content Security Policy (CSP) and HTTP Strict Transport Security (HSTS).

39. Secure API Authentication: Create a secure API authentication system using OAuth 2.0 or OpenID Connect.

40. Buffer Overflow Challenge: Attempt to exploit a buffer overflow vulnerability in a simple C program and discuss buffer overflow prevention.