Javascript MCQ

JavaScript MCQs

Practice JavaScript Multiple Choice Questions

MCQ 1

Question: Which JavaScript method can be used to convert a string into an array of characters?

• A. split()
• B. join()
• C. charAt()
• D. substr()

Answer: A. split()

MCQ 2

Question: What is the output of the following code snippet?

let x = 5;
let y = 10;
let z = x++ + y--;
console.log(z);

• A. 14
• B. 15
• C. 16
• D. 17

Answer: B. 15

Explanation: x++ increments after evaluation (x=6), y-- decrements after evaluation (y=9). Hence, z = 6 + 9 = 15.

MCQ 3

Question: What is the correct way to get an element with the ID myDiv using JavaScript?

• A. document.getElementById("myDiv")
• B. getElementById("myDiv")
• C. document.get("myDiv")
• D. document.find("myDiv")

Answer: A. document.getElementById("myDiv")

MCQ 4

Question: Given fruits = ["apple", "banana", "orange"], how can you create a new array containing only fruits that start with "a"?

• A. fruits.filter(fruit => fruit.startsWith("a"))
• B. fruits.map(fruit => fruit.startsWith("a"))
• C. fruits.reduce((acc, fruit) => fruit.startsWith("a") ? [...acc, fruit] : acc, [])
• D. fruits.forEach(fruit => fruit.startsWith("a") ? console.log(fruit) : null)

Answer: A. fruits.filter(fruit => fruit.startsWith("a"))

MCQ 5

Question: What is the output of the following code?

const numbers = [1, 2, 3, 4, 5];
const squaredNumbers = numbers.map(num => num * num);
console.log(squaredNumbers);

• A. [1, 4, 9, 16, 25]
• B. [2, 4, 6, 8, 10]
• C. [1, 2, 3, 4, 5]
• D. An error will be thrown

Answer: A. [1, 4, 9, 16, 25]