MCQs on Working with Strings and Numbers | JavaScript

“Working with Strings and Numbers” dives into the fundamentals of string and number manipulation in programming. Understanding string methods, template literals, number parsing, and basic math operations is crucial for data handling and creating dynamic applications. Below are 30 carefully curated multiple-choice questions, divided by topic for a focused learning experience.

String Methods

1. Which method returns the length of a string?
   • A) toUpperCase()
   • B) toLowerCase()
   • C) length
   • D) indexOf()
2. Which method would you use to convert a string to uppercase?
   • A) toUpperCase()
   • B) toLowerCase()
   • C) charAt()
   • D) slice()
3. Which method converts a string to lowercase?
   • A) concat()
   • B) toLowerCase()
   • C) includes()
   • D) toUpperCase()
4. What does the trim() method do to a string?
   • A) Removes all characters.
   • B) Adds spaces at the beginning and end.
   • C) Removes whitespace from both ends.
   • D) Replaces spaces with underscores.
5. What is the result of "hello".charAt(1)?
   • A) h
   • B) e
   • C) l
   • D) o
6. Which method can check if a string starts with a specified substring?
   • A) includes()
   • B) startsWith()
   • C) indexOf()
   • D) slice()
7. What will "JavaScript".indexOf("Script") return?
   • A) 4
   • B) 0
   • C) 5
   • D) 6
8. Which method would you use to split a string into an array?
   • A) split()
   • B) slice()
   • C) trim()
   • D) toLowerCase()
9. What does the replace() method do in a string?
   • A) Converts the string to lowercase.
   • B) Replaces the first occurrence of a substring with a new string.
   • C) Removes whitespace from both ends.
   • D) Changes the entire string.
10. Which of the following will capitalize only the first letter of the string "hello"?
    • A) "hello".toUpperCase()
    • B) "hello".charAt(0).toUpperCase() + "hello".slice(1)
    • C) "hello".toUpperCase() + "hello".slice(1)
    • D) "hello".slice(1)

Template Literals and String Interpolation

11. Which symbol is used to denote template literals in JavaScript?
    • A) '
    • B) "
    • C) {}
    • D) `
12. What will the output be for const name = "Alice"; const message = Hello, ${name}!;?
    • A) Hello, ${name}!
    • B) Hello, Alice!
    • C) Hello Alice!
    • D) ${name}, Hello!
13. Which is a key feature of template literals?
    • A) String methods
    • B) Interpolation of variables
    • C) Adding numbers
    • D) Changing case
14. What is the output of `The sum is: ${5 + 10}`?
    • A) The sum is: 15
    • B) The sum is: ${5 + 10}
    • C) The sum is 5 + 10
    • D) The sum: 15
15. How can multi-line strings be created in JavaScript?
    • A) Using + between strings
    • B) With single quotes
    • C) With double quotes
    • D) Using template literals

Number Methods

16. What is the output of parseInt("20.5")?
    • A) 20
    • B) 20.5
    • C) NaN
    • D) undefined
17. Which method can convert a string to a float number?
    • A) parseInt()
    • B) Number()
    • C) parseFloat()
    • D) toFixed()
18. What is the result of isNaN("Hello")?
    • A) true
    • B) false
    • C) NaN
    • D) undefined
19. Which method can detect if a value is not a number?
    • A) parseInt()
    • B) Number()
    • C) isNaN()
    • D) toString()
20. What will Number("50") + Number("10.5") return?
    • A) 60
    • B) 60.5
    • C) NaN
    • D) 510.5
21. Which of the following converts the string "123" to an integer?
    • A) parseInt("123")
    • B) parseFloat("123")
    • C) Number("123")
    • D) All of the above
22. What will parseFloat("10.99abc") return?
    • A) 10.99
    • B) NaN
    • C) 10
    • D) abc
23. Which of the following will return NaN?
    • A) Number("123a")
    • B) parseInt("123")
    • C) parseFloat("123.45")
    • D) Number("123")
24. Which method rounds a number to the nearest integer?
    • A) parseInt()
    • B) parseFloat()
    • C) Math.round()
    • D) Number()
25. Which of these methods can convert a number to a string?
    • A) parseInt()
    • B) Number()
    • C) toString()
    • D) isNaN()

Basic Math Object Methods

26. What does Math.max(3, 7, 1, 5) return?
    • A) 1
    • B) 3
    • C) 5
    • D) 7
27. Which of the following methods will return the smallest number in a list?
    • A) Math.round()
    • B) Math.ceil()
    • C) Math.min()
    • D) Math.max()
28. Which method returns the square root of a number?
    • A) Math.sqrt()
    • B) Math.pow()
    • C) Math.abs()
    • D) Math.floor()
29. What is the result of Math.floor(4.7)?
    • A) 4
    • B) 5
    • C) 4.7
    • D) NaN
30. Which method rounds a number up to the nearest integer?
    • A) Math.ceil()
    • B) Math.floor()
    • C) Math.round()
    • D) parseInt()

Answers