JavaScript Interview Questions For Freshers
  1. Discuss data types in JavaScript.
  2. Explain arrays in JavaScript and the process of creating one.
  3. Discuss the process of accessing elements of an array in JavaScript.
  4. Elaborate on the difference between the use of let, var and const
  5. Discuss strings in JavaScript and popular string methods.
  6. Explain the process of concatenating two strings in JavaScript.
  7. Explain objects in JavaScript and the process of creating one.
  8. Discuss functions in JavaScript and the process of creating one.
  9. Elaborate on callback functions in JavaScript.
  10. Discuss anonymous functions in JavaScript.
  11. List the different types of loops in JavaScript.
  12. Elaborate on if-else statements in JavaScript.
  13. Discuss switch statements in JavaScript.
  14. Explain the use of break and continue statements in JavaScript.
  15. Elaborate on the use of try-catch statements in JavaScript.
  16. Discuss the use of the throw statement in JavaScript.
  17. Explain type coercion in JavaScript.
  18. Discuss type conversion in JavaScript.
  19. Explain the parseInt() parseFloat(), Number() and String() functions in JavaScript.
  20. Elaborate on the difference between == and === in JavaScript.
  21. Discuss the concept of null and undefined in JavaScript.
  22. Explain NaN in JavaScript.
  23. Discuss the concept of Infinity in JavaScript.
  24. Explain events in JavaScript.
  25. Discuss event handlers and important event-related methods in JavaScript
  26. Discuss the preventDefault and stopPropogation() methods in JavaScript.
  27. What is the Document Object Model (DOM) in JavaScript and how is it used in web development?
  28. How can you manipulate HTML elements using JavaScript and the DOM API?
  29. Elaborate on the difference between innerHTML and innerText in JavaScript.
  30. Elaborate on the difference between getElementById, getElementsByClassName, query selector and getElementsByTagName in JavaScript.
  31. Elaborate on the difference between onclick and addEventListener in JavaScript.
  32. Elaborate on the difference between onload and onreadystatechange in JavaScript.
  33. What is a closure in JavaScript?
  34. Can you explain how to use the arrow functions in ES6?
  35. Can you explain how to use the template literals in ES6?
  36. Can you explain how to use the destructuring assignment in ES6?
  37. Can you explain how to use the spread operator in ES6?
  38. Discuss the difference between the XMLHttpRequest object and the Fetch API in JavaScript and when you would use each.
  39. Explain how you can use the Fetch API to retrieve data from a server using a GET request in JavaScript.
JavaScript Intermediate Interview Questions
  1. Discuss the process of destructuring in JavaScript.
  2. Describe the map method and its usage in JavaScript.
  3. Explain the purpose and usage of the filter method in JavaScript.
  4. Outline the reduce method and its usage in JavaScript.
  5. Detail the forEach method and its application in JavaScript.
  6. Discuss the concept of arrow functions in JavaScript.
  7. Describe the purpose and usage of the let keyword in JavaScript.
  8. Explain the concept of the const keyword and its usage in JavaScript.
  9. Detail the concept of template literals in JavaScript.
  10. Discuss the concept of classes in JavaScript.
  11. Outline the steps to create a class in JavaScript.
  12. Describe inheritance in JavaScript.
  13. Detail the prototype concept in JavaScript.
  14. Explain the process of creating an object using a constructor in JavaScript.
  15. Outline the concept of constructors in JavaScript.
  16. Discuss the usage of the new operator in JavaScript.
  17. Describe the prototype chain in JavaScript.
  18. Detail the process of method overriding in JavaScript.
  19. Outline the concept of method overloading in JavaScript.
  20. Explain the set concept in JavaScript.
  21. Discuss the map concept in JavaScript.
  22. Detail the weak map concept in JavaScript.
  23. Outline the weak set concept in JavaScript.
  24. Explain the symbol concept in JavaScript.
  25. Describe the promise concept in JavaScript.
  26. Detail the async-await concept in JavaScript.
  27. Outline the generator concept in JavaScript.
  28. Discuss the usage of the yield keyword in JavaScript.
  29. Explain the usage of the next() method in JavaScript.
  30. Describe the proxy concept in JavaScript.
  31. Detail the reflect concept in JavaScript.
  32. Outline the usage of the apply() method in JavaScript.
  33. Discuss the usage of the call() method in JavaScript.
  34. Explain the usage of the bind() method in JavaScript.
  35. Describe the difference between call(), bind() and apply() in JavaScript.
  36. Explain the concept of modules in JavaScript.
  37. Discuss the exports concept in JavaScript.
  38. Describe the require concept in JavaScript.
  39. Detail the named export concept in JavaScript.
  40. Outline the default export concept in JavaScript.
  41. Explain the REST API concept in JavaScript.
  42. Discuss the SOAP API concept in JavaScript.
  43. Describe the AJAX concept in JavaScript.
  44. Detail the JSON concept in JavaScript.
  45. Outline the usage of JSON.stringify() in JavaScript.
  46. Explain the usage of JSON.parse() in JavaScript.
  47. Discuss the fetch API and its usage in JavaScript.
  48. How does inheritance work in JavaScript OOPs?
  49. Can you explain the difference between the class and the constructor in JavaScript OOPs?
  50. How does the prototype chain work in JavaScript OOPs?
  51. Can you explain what a polyfill is and how it works in JavaScript?
  52. Can you explain how to use the Modernizr library for checking the compatibility of APIs in JavaScript?
  53. Can you explain how to implement the localStorage API as a polyfill in JavaScript?
  54. Can you explain how to make an AJAX request in JavaScript?
  55. Can you explain how to handle the error cases in AJAX requests in JavaScript?
  56. Can you explain how to use the XHR object for making an AJAX request in JavaScript?
  57. Can you explain what throttling is and why it is used in JavaScript?
  58. Can you explain the difference between throttling and debouncing in JavaScript?
  59. Discuss the difference between inheritance and composition in JavaScript and provide examples of both.
  60. Explain the concept of Event Bubbling and Capturing in JavaScript and the DOM, and provide examples of each.
  61. How can you perform POST requests using the Fetch API in JavaScript?
  62. Discuss the difference between synchronous and asynchronous requests in JavaScript and why asynchronous requests are preferred in web development.
  63. Explain how you can handle errors in AJAX and Fetch requests in JavaScript, including handling 404 errors and timeouts.
JavaScript Interview Questions For Experienced
  1. What is hoisting in JavaScript and how does it work?
  2. What is the difference between .call() and .apply() methods in JavaScript?
  3. What is a IIFE (Immediately Invoked Function Expression) in JavaScript?
  4. What is the use of .map() method in JavaScript arrays?
  5. Can you explain the difference between .reduce() and .forEach() methods in JavaScript arrays?
  6. What is a higher-order function in JavaScript and what is it used for?
  7. What is the use of the Array.isArray() method in JavaScript?
  8. What is the use of the Array.of() method in JavaScript?
  9. Can you explain the difference between null and undefined in JavaScript?
  10. What is the difference between null and NaN in JavaScript?
  11. What is the use of the Array.from() method in JavaScript?
  12. What is the use of the Array.filter() method in JavaScript?
  13. What is a Promises in JavaScript and how does it work?
  14. Can you explain the difference between Promises and Callbacks in JavaScript?
  15. What is the use of the do-while loop in JavaScript?
  16. What is the use of the while loop in JavaScript?
  17. What is the use of the for loop in JavaScript?
  18. Can you explain the difference between for-in and for-of loops in JavaScript?
  19. What is the use of the continue statement in JavaScript?
  20. What is the use of the break statement in JavaScript?
  21. What is a regular expression in JavaScript and how does it work?
  22. Can you explain how to use the event delegation technique in JavaScript DOM events?
  23. Can you explain how to use the MutationObserver API for detecting changes in the HTML DOM in JavaScript?
  24. How can you implement multiple inheritance in JavaScript OOPs?
  25. Can you explain the difference between the mixins and traits in JavaScript OOPs?
  26. Can you explain how to use the Object.assign() method for implementing mixins in JavaScript OOPs?
  27. Can you explain how to implement the fetch API as a polyfill in JavaScript?
  28. Can you explain how to implement the Promises API as a polyfill in JavaScript?
  29. Can you explain the difference between shimming and polyfilling in JavaScript?
  30. Can you explain how to make a CORS (Cross-Origin Resource Sharing) request in JavaScript?
  31. Can you explain how to use the fetch API for making an AJAX request in JavaScript?
  32. Can you explain the difference between XHR and fetch API in JavaScript?
  33. Can you explain how to use the Map and Set data structures in ES6?
  34. Can you explain how to implement debouncing function in JavaScript?
  35. Can you explain the difference between a throttle and a rate limiter in JavaScript?
  36. Can you explain how to use throttle and debouncing for performance optimization in JavaScript?
  37. How can you implement polymorphism in JavaScript?
  38. What is the difference between classical inheritance and prototypal inheritance in JavaScript and when would you use each?
  39. Discuss the use of mixins in JavaScript and how they can be used to achieve multiple inheritance.