
Practice 100 JavaScript Basic Programming Questions
Q1. Write a JavaScript program to calculate the sum of two numbers.
Input:
let num1 = 5;
let num2 = 10;
Expected Output:
15
Q2. Write a JavaScript program to check if a given number is even or odd.
Input:
let num = 7;
Expected Output:
Odd
Q3. Write a JavaScript program to find the largest of three numbers.
Input:
let a = 12;
let b = 45;
let c = 32;
Expected Output:
45
Q4. Write a JavaScript program to reverse a string.
Input:
let str = "hello";
Expected Output:
"olleh"
Q5. Write a JavaScript program to check if a string is a palindrome.
Input:
let str = "radar";
Expected Output:
true
Q6. Write a JavaScript program to print numbers from 1 to 10 using a loop.
Expected Output:
1
2
3
4
5
6
7
8
9
10
Q7. Write a JavaScript program to check if a given number is positive, negative, or zero.
Input:
let num = -3;
Expected Output:
Negative
Q8. Write a JavaScript program to calculate the factorial of a number.
Input:
let num = 5;
Expected Output:
120
Q9. Write a JavaScript program to print the multiplication table of a number.
Input:
let num = 3;
Expected Output:
3 x 1 = 3
3 x 2 = 6
3 x 3 = 9
3 x 4 = 12
3 x 5 = 15
3 x 6 = 18
3 x 7 = 21
3 x 8 = 24
3 x 9 = 27
3 x 10 = 30
Q10. Write a JavaScript program to find the sum of all numbers in an array.
Input:
let arr = [1, 2, 3, 4, 5];
Expected Output:
15
Q11. Write a JavaScript program to find the largest number in an array.
Input:
let arr = [5, 12, 8, 20, 3];
Expected Output:
20
Q12. Write a JavaScript program to count the number of vowels in a string.
Input:
let str = "hello world";
Expected Output:
3
Q13. Write a JavaScript program to find the index of a specific value in an array.
Input:
let arr = [10, 20, 30, 40, 50];
let value = 30;
Expected Output:
2
Q14. Write a JavaScript program to remove duplicate values from an array.
Input:
let arr = [1, 2, 2, 3, 4, 4, 5];
Expected Output:
[1, 2, 3, 4, 5]
Q15. Write a JavaScript program to convert a temperature from Celsius to Fahrenheit.
Input:
let celsius = 25;
Expected Output:
77
Q16. Write a JavaScript program to check if a number exists in an array.
Input:
let arr = [10, 20, 30, 40, 50];
let num = 25;
Expected Output:
false
Q17. Write a JavaScript program to calculate the average of numbers in an array.
Input:
let arr = [10, 20, 30, 40, 50];
Expected Output:
30
Q18. Write a JavaScript program to capitalize the first letter of each word in a string.
Input:
let str = "hello world";
Expected Output:
"Hello World"
Q19. Write a JavaScript program to check if a number is a prime number.
Input:
let num = 7;
Expected Output:
true
Q20. Write a JavaScript program to merge two arrays and remove duplicate elements.
Input:
let arr1 = [1, 2, 3];
let arr2 = [3, 4, 5];
Expected Output:
[1, 2, 3, 4, 5]
Q21. Write a JavaScript program to calculate the power of a number.
Input:
let base = 2;
let exponent = 3;
Expected Output:
8
Q22. Write a JavaScript program to find the GCD (Greatest Common Divisor) of two numbers.
Input:
let num1 = 12;
let num2 = 15;
Expected Output:
3
Q23. Write a JavaScript program to check if a string contains a specific substring.
Input:
let str = "hello world";
let substring = "world";
Expected Output:
true
Q24. Write a JavaScript program to sort an array in ascending order.
Input:
let arr = [3, 1, 4, 1, 5, 9];
Expected Output:
[1, 1, 3, 4, 5, 9]
Q25. Write a JavaScript program to generate a random number between two values.
Input:
let min = 1;
let max = 10;
Expected Output:
Random number between 1 and 10 (inclusive)
Q26. Write a JavaScript program to find the second largest number in an array.
Input:
let arr = [10, 20, 4, 45, 99];
Expected Output:
45
Q27. Write a JavaScript program to count the number of occurrences of a specific element in an array.
Input:
let arr = [1, 2, 3, 1, 4, 1, 5];
let element = 1;
Expected Output:
3
Q28. Write a JavaScript program to check if an array is sorted in ascending order.
Input:
let arr = [1, 2, 3, 4, 5];
Expected Output:
true
Q29. Write a JavaScript program to calculate the sum of the digits of a number.
Input:
let num = 12345;
Expected Output:
15
Q30. Write a JavaScript program to find the smallest number in an array.
Input:
let arr = [3, 1, 4, 1, 5, 9];
Expected Output:
1
Q31. Write a JavaScript program to remove all falsy values from an array.
Input:
let arr = [0, 1, false, 2, "", 3, undefined];
Expected Output:
[1, 2, 3]
Q32. Write a JavaScript program to find the length of the longest word in a string.
Input:
let str = "The quick brown fox jumps over the lazy dog";
Expected Output:
5
Q33. Write a JavaScript program to generate the first `n` Fibonacci numbers.
Input:
let n = 5;
Expected Output:
[0, 1, 1, 2, 3]
Q34. Write a JavaScript program to flatten a nested array.
Input:
let arr = [1, [2, [3, [4, 5]]]];
Expected Output:
[1, 2, 3, 4, 5]
Q35. Write a JavaScript program to check if two arrays are equal.
Input:
let arr1 = [1, 2, 3];
let arr2 = [1, 2, 3];
Expected Output:
true
Q36. Write a JavaScript program to convert a string to title case (capitalize each word).
Input:
let str = "javascript is fun";
Expected Output:
"Javascript Is Fun"
Q37. Write a JavaScript program to find all unique values in an array.
Input:
let arr = [1, 2, 2, 3, 4, 4, 5];
Expected Output:
[1, 2, 3, 4, 5]
Q38. Write a JavaScript program to check if a number is divisible by both 3 and 5.
Input:
let num = 15;
Expected Output:
true
Q39. Write a JavaScript program to round a number to 2 decimal places.
Input:
let num = 3.14159;
Expected Output:
3.14
Q40. Write a JavaScript program to count the number of words in a string.
Input:
let str = "The quick brown fox";
Expected Output:
4
Q41. Write a JavaScript program to remove a specific element from an array.
Input:
let arr = [1, 2, 3, 4, 5];
let element = 3;
Expected Output:
[1, 2, 4, 5]
Q42. Write a JavaScript program to calculate the sum of squares of numbers in an array.
Input:
let arr = [1, 2, 3, 4];
Expected Output:
30
Q43. Write a JavaScript program to reverse the digits of a number.
Input:
let num = 12345;
Expected Output:
54321
Q44. Write a JavaScript program to find the first non-repeating character in a string.
Input:
let str = "swiss";
Expected Output:
"w"
Q45. Write a JavaScript program to find the sum of even numbers in an array.
Input:
let arr = [1, 2, 3, 4, 5, 6];
Expected Output:
12
Q46. Write a JavaScript program to convert a number to its binary representation.
Input:
let num = 10;
Expected Output:
"1010"
Q47. Write a JavaScript program to find the most frequent element in an array.
Input:
let arr = [1, 2, 2, 3, 3, 3, 4];
Expected Output:
3
Q48. Write a JavaScript program to calculate the product of all numbers in an array.
Input:
let arr = [1, 2, 3, 4];
Expected Output:
24
Q49. Write a JavaScript program to find the median of an array.
Input:
let arr = [1, 3, 3, 6, 7, 8, 9];
Expected Output:
6
Q50. Write a JavaScript program to rotate an array `k` times to the right.
Input:
let arr = [1, 2, 3, 4, 5];
let k = 2;
Expected Output:
[4, 5, 1, 2, 3]
Q51. Write a JavaScript program to check if a string is a palindrome.
Input:
let str = "radar";
Expected Output:
true
Q52. Write a JavaScript program to count the frequency of each character in a string.
Input:
let str = "hello";
Expected Output:
{ h: 1, e: 1, l: 2, o: 1 }
Q53. Write a JavaScript program to convert the first character of a string to uppercase.
Input:
let str = "javascript";
Expected Output:
"Javascript"
Q54. Write a JavaScript program to generate a multiplication table for a given number.
Input:
let num = 5;
Expected Output:
[5, 10, 15, 20, 25, 30, 35, 40, 45, 50]
Q55. Write a JavaScript program to find the largest element in a 2D array.
Input:
let arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9]
];
Expected Output:
9
Q56. Write a JavaScript program to calculate the factorial of a number using recursion.
Input:
let num = 5;
Expected Output:
120
Q57. Write a JavaScript program to find the longest word in a string.
Input:
let str = "The quick brown fox jumped over the lazy dog";
Expected Output:
"jumped"
Q58. Write a JavaScript program to check if all elements in an array are unique.
Input:
let arr = [1, 2, 3, 4, 5];
Expected Output:
true
Q59. Write a JavaScript program to find the transpose of a 2D array.
Input:
let arr = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9]
];
Expected Output:
[
[1, 4, 7],
[2, 5, 8],
[3, 6, 9]
]
Q60. Write a JavaScript program to shuffle the elements of an array randomly.
Input:
let arr = [1, 2, 3, 4, 5];
Expected Output:
Randomized array (e.g., [3, 5, 1, 2, 4])
Q61. Write a JavaScript program to find the difference between the maximum and minimum elements in an array.
Input:
let arr = [10, 20, 30, 40, 50];
Expected Output:
40
Q62. Write a JavaScript program to capitalize the first letter of each word in a string.
Input:
let str = "javascript is awesome";
Expected Output:
"Javascript Is Awesome"
Q63. Write a JavaScript program to merge two arrays and remove duplicate elements.
Input:
let arr1 = [1, 2, 3];
let arr2 = [2, 3, 4];
Expected Output:
[1, 2, 3, 4]
Q64. Write a JavaScript program to check if a number is prime.
Input:
let num = 7;
Expected Output:
true
Q65. Write a JavaScript program to reverse a string.
Input:
let str = "hello";
Expected Output:
"olleh"
Q66. Write a JavaScript program to generate an array of random numbers of length `n`.
Input:
let n = 5;
Expected Output:
[Random numbers, e.g., [4, 8, 2, 9, 1]]
Q67. Write a JavaScript program to find the second smallest element in an array.
Input:
let arr = [5, 3, 8, 1, 4];
Expected Output:
3
Q68. Write a JavaScript program to check if a string ends with a specific substring.
Input:
let str = "hello world";
let substring = "world";
Expected Output:
true
Q69. Write a JavaScript program to check if an object is empty.
Input:
let obj = {};
Expected Output:
true
Q70. Write a JavaScript program to count the vowels in a string.
Input:
let str = "javascript";
Expected Output:
3
Q71. Write a JavaScript program to find the greatest common divisor (GCD) of two numbers.
Input:
let num1 = 56;
let num2 = 98;
Expected Output:
14
Q72. Write a JavaScript program to sort an array of strings alphabetically.
Input:
let arr = ["banana", "apple", "cherry"];
Expected Output:
["apple", "banana", "cherry"]
Q73. Write a JavaScript program to check if a number is a power of 2.
Input:
let num = 16;
Expected Output:
true
Q74. Write a JavaScript program to find the sum of the digits of a number.
Input:
let num = 1234;
Expected Output:
10
Q75. Write a JavaScript program to check if two strings are anagrams.
Input:
let str1 = "listen";
let str2 = "silent";
Expected Output:
true
Q76. Write a JavaScript program to find the index of the first occurrence of a number in an array.
Input:
let arr = [10, 20, 30, 40, 50];
let target = 30;
Expected Output:
2
Q77. Write a JavaScript program to find the square root of a number without using the `Math.sqrt()` function.
Input:
let num = 16;
Expected Output:
4
Q78. Write a JavaScript program to calculate the sum of the first `n` natural numbers.
Input:
let n = 5;
Expected Output:
15
Q79. Write a JavaScript program to check if an array contains all odd numbers.
Input:
let arr = [1, 3, 5, 7];
Expected Output:
true
Q80. Write a JavaScript program to find the largest number in an array without using built-in functions.
Input:
let arr = [10, 25, 5, 45, 30];
Expected Output:
45
Q81. Write a JavaScript program to check if a string starts with a specific substring.
Input:
let str = "hello world";
let substring = "hello";
Expected Output:
true
Q82. Write a JavaScript program to count the number of words in a string.
Input:
let str = "JavaScript is amazing";
Expected Output:
3
Q83. Write a JavaScript program to find the cumulative sum of an array.
Input:
let arr = [1, 2, 3, 4];
Expected Output:
[1, 3, 6, 10]
Q84. Write a JavaScript program to flatten a 2D array into a 1D array.
Input:
let arr = [
[1, 2],
[3, 4],
[5, 6]
];
Expected Output:
[1, 2, 3, 4, 5, 6]
Q85. Write a JavaScript program to remove all falsy values from an array.
Input:
let arr = [0, 1, false, 2, "", 3];
Expected Output:
[1, 2, 3]
Q86. Write a JavaScript program to find the intersection of two arrays.
Input:
let arr1 = [1, 2, 3, 4];
let arr2 = [3, 4, 5, 6];
Expected Output:
[3, 4]
Q87. Write a JavaScript program to split a string into an array of words.
Input:
let str = "Split this string";
Expected Output:
["Split", "this", "string"]
Q88. Write a JavaScript program to find the length of the longest word in a string.
Input:
let str = "JavaScript is powerful";
Expected Output:
10
Q89. Write a JavaScript program to repeat a string `n` times.
Input:
let str = "abc";
let n = 3;
Expected Output:
"abcabcabc"
Q90. Write a JavaScript program to calculate the sum of the diagonal elements in a 2D square matrix.
Input:
let matrix = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9]
];
Expected Output:
15
Q91. Write a JavaScript program to remove duplicate elements from an array.
Input:
let arr = [1, 2, 2, 3, 4, 4, 5];
Expected Output:
[1, 2, 3, 4, 5]
Q92. Write a JavaScript program to count the occurrences of a specific element in an array.
Input:
let arr = [1, 2, 2, 3, 4, 2];
let target = 2;
Expected Output:
3
Q93. Write a JavaScript program to reverse the elements of an array without using `reverse()`.
Input:
let arr = [1, 2, 3, 4, 5];
Expected Output:
[5, 4, 3, 2, 1]
Q94. Write a JavaScript program to calculate the sum of even numbers in an array.
Input:
let arr = [1, 2, 3, 4, 5, 6];
Expected Output:
12
Q95. Write a JavaScript program to find the first non-repeating character in a string.
Input:
let str = "swiss";
Expected Output:
"w"
Q96. Write a JavaScript program to convert an array of numbers into an array of their squares.
Input:
let arr = [1, 2, 3, 4];
Expected Output:
[1, 4, 9, 16]
Q97. Write a JavaScript program to check if a number is a perfect square.
Input:
let num = 25;
Expected Output:
true
Q98. Write a JavaScript program to calculate the average of numbers in an array.
Input:
let arr = [10, 20, 30, 40];
Expected Output:
25
Q99. Write a JavaScript program to rotate the elements of an array `n` times to the right.
Input:
let arr = [1, 2, 3, 4, 5];
let n = 2;
Expected Output:
[4, 5, 1, 2, 3]
Q100. Write a JavaScript program to remove all instances of a specific element from an array.
Input:
let arr = [1, 2, 3, 2, 4, 2];
let target = 2;
Expected Output:
[1, 3, 4]