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Javascript MCQ Questions | Interview Quick

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Javascript MCQ

1. Which operator returns true if the two compared values are not equal?

2. How is a forEach statement different from a for statement?

3. Which statement is the correct way to create a variable called rate and assign it the value 100?

4. Which statement creates a new object using the Person constructor? Which statement creates a new Person object called "student"?

5. How does a function create a closure?

6. . Which statement creates a new function called discountPrice?

7. . You need to match a time value such as 12:00:32. Which of the following regular expressions would work for your code?

8. . Which property references the DOM object that dispatched an event?

9. . Which method converts JSON data to a JavaScript object?

10. . When would you use a conditional statement?

11. Which Object method returns an iterable that can be used to iterate over the properties of an object?

12. What is one difference between collections created with Map and collections created with Object?

13. 0 && hi

14. Which of the following operators can be used to do a short-circuit evaluation?

15. Which statement sets the Person constructor as the parent of the Student constructor in the prototype chain?

16. Why would you include a "use strict" statement in a JavaScript file?

17. Which Variable-defining keyword allows its variable to be accessed (as undefined) before the line that defines it?

18. Which of the following values is not a Boolean false?

19. Which of the following is not a keyword in JavaScript?

20. Which variable is an implicit parameter for every function in JavaScript?

21. Why is it usually better to work with Objects instead of Arrays to store a collection of records?

22. Which statement is true about the "async" attribute for the HTML script tag?

23. How do you import the lodash library making it top-level Api available as the "_" variable?

24. What type of function can have its execution suspended and then resumed at a later point?

25. Which statement is true about Functional Programming?

26. Your code is producing the error: TypeError: Cannot read property 'reduce' of undefined. What does that mean?

27. Which choice is not a unary operator?

28. Which keyword is used to create an error?

29. What's one difference between the async and defer attributes of the HTML script tag?

30. Which collection object allows unique value to be inserted only once?

31. How does the forEach() method differ from a for statement?

32. Which choice is an incorrect way to define an arrow function that returns an empty object?

33. Why might you choose to make your code asynchronous?

34. Which expression evaluates to true?

35. Which of these is a valid variable name?

36. Which method cancels event default behavior?

37. Which method do you use to attach one DOM node to another?

38. What statement can be used to skip an iteration in a loop?

39. Which choice is valid example for an arrow function?

40. Which concept is defined as a template that can be used to generate different objects that share some shape and/or behavior?

41. How do you add a comment to JavaScript code?

42. If you attempt to call a value as a function but the value is not a function, what kind of error would you get?

43. Which method is called automatically when an object is initialized?

44. Which statement represents the starting code converted to an IIFE?

45. Which statement selects all img elements in the DOM tree?

46. Why would you choose an asynchronous structure for your code?

47. What is the HTTP verb to request the contents of an existing resource?

48. Which event is fired on a text field within a form when a user tabs to it, or clicks or touches it?

49. What is the difference between the map() and the forEach() methods on the Array prototype?

50. Which tag pair is used in HTML to embed JavaScript?

51. If your app receives data from a third-party API, which HTTP response header must the server specify to allow exceptions to the same-origin policy?

52. Which statement can take a single expression as input and then look through a number of choices until one that matches that value is found?

53. Which choice is a valid example of an arrow function, assuming c is defined in the outer scope?

54. Which method call is chained to handle a successful response returned by fetch()?

55. Which choice is not an array method?

56. Which JavaScript loop ensures that at least a singular iteration will happen?

57. Which value is not falsey?

58. Which of these evaluate to true?

59. Which method converts a JSON string to a Javascript object?

60. Which method do you use to attach one DOM mode to another?

61. How would you add a data item named animal with a value of sloth to local storage for the current domain?

62. Which document method is not used to get a reference to a DOM node?

63. In JavaScript, all objects inherit a built-in property from a ****___****.

64. Which of the following are not server-side Javascript objects?

65. Which object in Javascript doesn’t have a prototype?

66. What does … operator do in JS?

67. How to stop an interval timer in Javascript?

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