Get Ready for Your JavaScript Interview: Top 100 Questions to Practice
Tags: javascript, node, beginners, tutorial
Published: 2024-06-17 02:14:49

JavaScript is a crucial skill for any developer, and mastering it can open doors to exciting career opportunities. Whether you're preparing for your first JavaScript interview or aiming to brush up on your skills, here are 100 essential questions that can help you ace your interview:

1. What is JavaScript?
2. What are the key differences between JavaScript and Java?
3. What are the data types in JavaScript?
4. Explain the concept of hoisting in JavaScript.
5. How does JavaScript handle asynchronous operations?
6. What are closures in JavaScript?
7. What is the prototype chain in JavaScript?
8. How do you check the type of a variable in JavaScript?
9. Explain the event bubbling and capturing in JavaScript.
10. How does prototypal inheritance differ from classical inheritance?
11. What is the difference between `==` and `===` operators?
12. How does `setTimeout` function work in JavaScript?
13. Explain the concept of promises in JavaScript.
14. What are arrow functions in JavaScript?
15. How does `this` keyword work in JavaScript?
16. What is the use of `bind` method in JavaScript?
17. How can you create a closure in JavaScript?
18. What is the difference between `null` and `undefined`?
19. Explain the concept of event delegation in JavaScript.
20. What is the difference between synchronous and asynchronous JavaScript?
21. How do you handle errors in JavaScript?
22. What are higher-order functions in JavaScript?
23. Explain the difference between function declaration and function expression.
24. How can you achieve inheritance in JavaScript?
25. What are the different ways to declare a variable in JavaScript?
26. Explain the use of `map`, `filter`, and `reduce` functions.
27. What is the purpose of `JSON.stringify` and `JSON.parse` in JavaScript?
28. How can you prevent the default behavior of an event in JavaScript?
29. Explain the concept of memoization in JavaScript.
30. What are the different types of scopes in JavaScript?
31. How does the ES6 module system differ from CommonJS?
32. What are the rest parameters in JavaScript?
33. How do you handle CORS in JavaScript?
34. Explain the use of `async` and `await` in JavaScript.
35. What are generator functions in JavaScript?
36. How can you convert a callback-based function to a promise-based function?
37. Explain the concept of currying in JavaScript.
38. What is the difference between `let`, `const`, and `var` in JavaScript?
39. How can you detect if a variable is an array in JavaScript?
40. Explain the purpose of the `Symbol` data type in JavaScript.
41. What is a closure trap in JavaScript?
42. How do you handle memory leaks in JavaScript?
43. Explain the use of `try`, `catch`, and `finally` in error handling.
44. What is the purpose of the `use strict` directive in JavaScript?
45. How can you check if an object has a property in JavaScript?
46. Explain the concept of event loop in JavaScript.
47. What are the differences between `forEach` and `map` methods?
48. How can you copy an object in JavaScript?
49. Explain the differences between `slice` and `splice` methods.
50. What is the purpose of the `WeakMap` and `WeakSet` in JavaScript?
51. How can you merge two arrays in JavaScript?
52. Explain the purpose of the `Symbol.iterator` method in JavaScript.
53. What are the different ways to create an object in JavaScript?
54. How can you validate an email address in JavaScript?
55. Explain the purpose of the `includes` method in arrays.
56. What are the differences between `==` and `===` operators in JavaScript?
57. How can you create a private variable in JavaScript?
58. Explain the purpose of the `Object.keys` method in JavaScript.
59. What are the differences between `null`, `undefined`, and `undeclared` in JavaScript?
60. How can you convert a string to a number in JavaScript?
61. Explain the purpose of the `Array.isArray` method in JavaScript.
62. What are the differences between function declaration and function expression in JavaScript?
63. How can you convert JSON to a JavaScript object?
64. Explain the purpose of the `Array.prototype.map` method in JavaScript.
65. What are the differences between `let`, `const`, and `var` in JavaScript?
66. How can you sort an array of objects by a specific property in JavaScript?
67. Explain the purpose of the `Array.prototype.filter` method in JavaScript.
68. What are the differences between `==` and `===` operators in JavaScript?
69. How can you remove duplicates from an array in JavaScript?
70. Explain the purpose of the `Array.prototype.reduce` method in JavaScript.
71. What are the differences between `null`, `undefined`, and `undeclared` in JavaScript?
72. How can you check if a string contains a substring in JavaScript?
73. Explain the purpose of the `Array.prototype.forEach` method in JavaScript.
74. What are the differences between `let`, `const`, and `var` in JavaScript?
75. How can you reverse a string in JavaScript?
76. Explain the purpose of the `Array.prototype.indexOf` method in JavaScript.
77. What are the differences between `==` and `===` operators in JavaScript?
78. How can you find the largest and smallest numbers in an array in JavaScript?
79. Explain the purpose of the `Array.prototype.some` method in JavaScript.
80. What are the differences between `null`, `undefined`, and `undeclared` in JavaScript?
81. How can you capitalize the first letter of a string in JavaScript?
82. Explain the purpose of the `Array.prototype.every` method in JavaScript.
83. What are the differences between `let`, `const`, and `var` in JavaScript?
84. How can you remove falsy values from an array in JavaScript?
85. Explain the purpose of the `Array.prototype.slice` method in JavaScript.
86. What are the differences between `==` and `===` operators in JavaScript?
87. How can you flatten an array in JavaScript?
88. Explain the purpose of the `Array.prototype.sort` method in JavaScript.
89. What are the differences between `null`, `undefined`, and `undeclared` in JavaScript?
90. How can you shuffle an array in JavaScript?
91. Explain the purpose of the `Array.prototype.reverse` method in JavaScript.
92. What are the differences between `let`, `const`, and `var` in JavaScript?
93. How can you find the intersection of two arrays in JavaScript?
94. Explain the purpose of the `Array.prototype.join` method in JavaScript.
95. What are the differences between `==` and `===` operators in JavaScript?
96. How can you find the union of two arrays in JavaScript?
97. Explain the purpose of the `Array.prototype.splice` method in JavaScript.
98. What are the differences between `null`, `undefined`, and `undeclared` in JavaScript?
99. How can you create a random number between two numbers in JavaScript?
100. Explain the purpose of the `Array.prototype.concat` method in JavaScript.

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These questions cover a wide range of topics and are designed to help you solidify your understanding of JavaScript concepts. Make sure to practice answering them and understand the underlying principles to confidently tackle any JavaScript interview. Good luck!