JavaScript Interview Questions For 3 Years Of Experience

JavaScript Interview Questions

1. What is Callback hell ?
2. Explain promises in JavaScript ?
3. Difference between observable and a promise
4. How to create custom events in JavaScript ?
5. Difference between prototype and _proto_ ?
6. Explain prototypal inheritance in JavaScript ?
7. Difference between for in and for of loop ?
8. Difference between get and post methods ?
9. Difference between post and put methods ?
10. When we pass an object to a function are they passed by reference or by value ?
11. What are the design patterns in JavaScript ?
12. What do u understand by the terms mutable and immutable in JavaScript ?
13. What is Async and Await in JavaScript ?
14. Is array a data type ?
15. How can we overwrite any JavaScript inbuilt property (like array.push())
16. Explain exception handling in JavaScript ?
17. Difference between a transpiler and a compiler ?
18. How to apply conditional breakpoints in chrome browser debugging tool ?
19. How to check if a number is an integer without using math function and without converting number into string or array ?
20. Use of JavaScript clearInterval() ?
21. How to define a private method or variable inside a class in JavaScript or ES6 ?
22. Can arrow functions be used as constructor functions ?
23. What is Map in JavaScript ?
24. How to implement authentication in a website ?
25. How would you implement pagination using JavaScript ?
26. Difference between a browser tab and a window in context of localstorage and sessionstorage ?
27. What is oauth in context of jwt ?
28. What is nginx used for ?
29. How to change the redirection URLs after the build has been made ?
30. What is a JWT , what are it’s parts and what is its use ?
31. What are ‘set’ in javascript ?
32. Do we have reverse() method on javascript string ?
33. Name some array methods in JavaScript ?
34. Which operation is faster among == and === ?
35. Why storing JWT in cookie is safer than storing JWT in session storage or local storage? Is storing in cookie 100 percent safe ? what if I copy JWT from cookie in the browser debug panel and use it in a CSRF attack ?
36. Explain Array’s sort method for sorting numbers. What is the time complexity of this method ?
37. What is quick sort and what is it’s time complexity ?
38. Write a code to flatten the contents of an object ?
39. What is Micro frontend architecture ?
40. What is the difference between first class function and higher order function ?
41. What is temporal dead zone ?
42. What is the seal method in JavaScript ?
43. What is functional programming in JavaScript ?
44. Difference between put and patch method in javascript ?
45. What is a REST API ?
46. How to convert an object to an Array in JavaScript ?
47. How to deep clone in JavaScript ?
48. How to flatten an array in JavaScript ?
49. What is debounce in JavaScript ?
50. What is memoization in JavaScript ?
51. How to write a function ‘Sum’ such that on calling sum(a)(b)©….() where a,b,c etc are numbers , the output will be a+b+c+….(function calls with parameters) ?
52. What will be the output of the below code:

let obj ={
a: 10,
vir : function(){
  x();
  console.log(this.a); 
  function x(){
  console.log(this.a)
  }
 }
}
obj.vir();

Source:- JavaScript Interview Questions For 3 Years Of Experience

For more questions and answers visit our website at Frontend Interview Questions