JavaScript Developer Interview Questions for Freshers

1. What are the data types in JavaScript ?
2. What is an object in JavaScript ?
3. In how many ways we can define an object in JavaScript ?
4. How to define a class in JavaScript ?
5. What is defineProperty() method of javascript Object ?
6. What is scope in JavaScript ?
7. Explain variable hoisting ?
8. Explain closures in javascript ?
9. Difference between null and undefined ?
10. Difference between == and === ?
11. What are the new features in ES6 , which were not there in previous JavaScript version ?
12. Explain time complexity ?
13. What is space complexity ?

14. 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();

15. What will be the output of the below code for (var i= 0; i < 5; i++){ setTimeout(() => console.log(i)); }
16. What will be the output of the below code :- var a = 90; doit(); function doit(){ console.log(a); var a = 10; }
17. Explain call(), bind() and apply() in JavaScript ?
18. Advantage of using arrow functions ?
19. What is webpack and babel ?
20. How can we add an element at the start of a JavaScript array ?
21. How to capitalise all the first letters of a given string ?
22. What will be output of following code doit(); var doit = function (){ alert('x'); }
23. Difference between pass by value and pass by reference ?
24. What will be the output of following code:- for (var i= 0; i < 5; i++){ (function(i) { setTimeout( () => console.log(i)) })(i); }
25. What is InstanceOf operator ?
26. What is the use of constructor() in a class ?
27. What will be the output of the following :console.log(4.toString());console.log(4.2.toString());console.log(4*undefined);
28. How can we use javascript Set to remove duplicate elements of an array ?
29. What is the data storage limit of a cookie ? and what is the maximum number of characters that can be stored in a cookie string ?
30. How to make deep copy and shallow copy of objects ?
31. What's the difference between for loop and for each loop ?
32. What is a unary function ?
33. What is JSON in javascript and what are its advantages ?
34. What is JSON.stringify() ?
35. What is JSON.parse() ?

Source:- JavaScript Developer Interview Questions for Freshers 

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