100 Javascript Interview questions to Crack any Javascript Interview

100 Javascript interview questions that i prepared for clearing javascript interviews in MS/Walmart/Paytm/Flipkart etc. This set of Javascript interview questions will work for any Software Engineer level Front End interviews.

100 Javascript Interview questions to Crack any Javascript Inteview

  1. Data Types in JS
  2. Falsy Values
  3. Map, Reduce, Filter functionalities
  4. Prototypical Inheritance in Javascript
  5. Generator Function (function()*, yield)
  6. Caching based questions (Headers, Expiry, Types etc)
  7.  PWA & TWA ( Caching, Service Workers, Manifest File)
  8. Server Side Rendering
  9. Throttle & Debounce, important concept for Front End developer interview
  10. Iterators in Javascript
  11. Pollyfills for in built functions
  12. Split, Replace, Splice, Slice
  13. Query Selector in Javascript
  14. Substring, Trim and other string operations
  15. Typeof related output questions
  16. HTML5 features
  17. Web worker based Javascript Interview Questions
  18. Scoping in Javascript (this)
  19. Closure
  20. How to Memoize any Javascript Function - Memoization
  21. Hoisting
  22. Design Patterns in Javascript( Modular, Factory, Observer, Pub Sub, Singleton etc)
  23. Currying - add(1)(3)(4)..(n)() and other variations
  24. Call, Apply, Bind based javascript interview questions
  25. Prototype Chain in Javascript
  26. Declaring and extending classes using functions (ES6 to ES5)
  27. Levels of Javascript Scoping
  28. Arrow functions scope
  29. WSS and WS sockets
  30. Promises (all, finally etc) based Javascript interview questions
  31. Deep vs Shallow Copy in Javascript
  32. Binary Search based questions
  33. Deleting Object Keys
  34. HasOwnProperty in Javascript Objects
  35. Two way binding implementation
  36. Implicit/Hard/Explicit/New Binding
  37. Callback to Promise conversion
  38. Callback hell
  39. Async/Await over Promise
  40. Eval Function
  41. isExtensible, freeze, sealed and other Javascript Object methods
  42. In built sort() with numbers
  43. Local Storage, Session Storage, Cookie etc(types of storage)
  44. Javascript:void(0)
  45. Event Bubbling, Event Capture, Event Delegation
  46. Difference between var vs let
  47. Output based questions on undefined vs reference error
  48. some, find, includes and other in built Javascript methods
  49. Oninput Event
  50. Anonymous function
  51. Flatten a nested array in Javascript
  52. Private Variable in Javascript
  53. Destructing
  54. Rest Operators
  55. Async vs defer in script tag
  56. Fetch() in Javascript
  57. Single page application architecture
  58. SPA effect on Search Engine Optimization
  59. XHR requests
  60. Event Loop based Javascript interview questions
  61. Message Queue
  62. Job Queue
  63. Call Stack
  64. What is a Tick?
  65. Decimal to Hexadecimal conversions
  66. Why do we use "use strict"
  67. Shift/Unshift in Arrays based Javascript interview questions
  68. Escape/Unescape
  69. Encode URI
  70. Data-ng attributes
  71. Dom tree implementation
  72. Reactive Programming
  73. React based javascript interview questions
  74. Virtual DOM Implementation of React
  75. Hooks - Usestate, useeffect, useref, useCallback, useMemo
  76. Pure Components
  77. Higher Order Components
  78. Styled Components
  79. Context API
  80. Redux based javascript interview questions
  81. Design Pattern behind redux
  82. Shadow DOM
  83. Frameworks specific questions based on your resume
  84. JS events(onkeyup, onkeydown, onmouseover etc)
  85. Finding document width/height
  86. Functional programming methodologies
  87. Accessing nested objects and listing all key value pairs
  88. Load balancers
  89. Scaling applications
  90. How does CDN works?
  91. Implementation of linked lists in JS
  92. All ES6 features
  93. JSON parse, stringify etc
  94. How does webpack works(dependency graph, chunk formation etc)?
  95. How does babel works?
  96. Node JS based basic javascript interview questions
  97. Deprecated react lifecycles and their drawbacks?
  98. Optimization of the problems that you are going to solve
  99. Frameworks vs VanillaJS
  100. Every word you say will be or can be used as a counter question so don't bring any new topic that you aren't confident about.
I have considered questions from all the companies that i interviewed including the one's i didn't crack. I cleared Javascript based rounds in last 7 companies. Mind you that there will be another 2/3 rounds based on Data Structure, Machine coding, Application design etc. HTML, CSS also plays a key role in Front End Interviews, so you should have good knowledge of HTML, CSS based Frontend Interview Questions. I received offers from 5 out of 7 companies including global giants.

So, i guess you would have liked my post on 100 Javascript Interview questions to Crack any Javascript Interview. Kindly do comment about anything that i missed. If you want me to share front end interview questions and experience with all the major companies then do let me know in comments.

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  1. Did you appear for Flipkart UI Engineer? If yes please share experience.

    1. Yes, I have. I will share the experience this weekend. Subscribe to this blog or follow me on Twitter to stay updated.


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