JavaScript Foundations: Basics and Core Concepts Quiz Quiz

1. Introduction to JavaScript

   Which of the following statements is true about where JavaScript code can run?

   1. B. Only inside databases
   2. A. Only in document editors
   3. E. Only within spreadsheets
   4. C. Both in web browsers and on servers
   5. D. Only in desktop applications

2. Syntax u0026 Comments

   How do you write a single-line comment in JavaScript code?

   1. D. ** this is a comment **
   2. A. u003C!-- this is a comment --u003E
   3. E. ;; this is a comment
   4. C. // this is a comment
   5. B. ## this is a comment

3. Variables - let

   Which keyword should you use to declare a variable that can be reassigned, such as let x = 5?

   1. B. vlet
   2. A. varible
   3. C. let
   4. E. vart
   5. D. const

4. Variables - const

   What happens if you try to reassign a variable declared with const in JavaScript?

   1. A. The value updates silently
   2. B. The statement is ignored without any warning
   3. C. A syntax error is thrown
   4. D. The program renames the variable automatically
   5. E. It changes type automatically

5. Variables - var

   Which JavaScript keyword declares a variable with function scope and allows re-declaration?

   1. A. var
   2. D. val
   3. C. vart
   4. B. let
   5. E. kon

6. Data Types - String

   Given the code let name = 'Sara';, which JavaScript type does variable name hold?

   1. A. string
   2. C. boolean
   3. E. null
   4. B. number
   5. D. array

7. Data Types - Number

   What value will typeof 42 return in JavaScript?

   1. C. 'boolean'
   2. D. 'function'
   3. B. 'number'
   4. E. 'object'
   5. A. 'string'

8. Type Conversion

   What will JavaScript return for Number('25')?

   1. C. 25
   2. E. NaN
   3. B. '25'
   4. D. null
   5. A. 0

9. Type Conversion - toString

   Which method converts a number to a string in JavaScript, such as (22).toString()?

   1. E. stringy()
   2. A. str()
   3. D. numberToString()
   4. C. toString()
   5. B. toText()

10. Operators - Arithmetic

    What is the result of the JavaScript expression 3 + 4 * 2?

    1. E. 8
    2. B. 10
    3. D. 7
    4. A. 14
    5. C. 11

11. Operators - Comparison

    Which operator checks for both value and type equality, such as 5 === '5'?

    1. B. !=
    2. A. ==
    3. C. equals
    4. E. =u003E
    5. D. ===

12. Operators - Logical

    Which symbol represents the logical AND operator in JavaScript?

    1. C. ^^
    2. E. !u0026
    3. A. u0026u0026
    4. D. u0026
    5. B. ||

13. Operators - Logical

    What is the result of false || true in JavaScript?

    1. D. false
    2. E. null
    3. C. true
    4. A. undefined
    5. B. 0

14. Operators - Bitwise

    Which bitwise operator performs a bitwise OR between two numbers in JavaScript?

    1. A. u0026
    2. C. |
    3. B. ^
    4. E. u0026u0026
    5. D. ~

15. Keywords and Identifiers

    Which of these is NOT a valid variable name in JavaScript?

    1. D. $result
    2. C. 2total
    3. E. userName
    4. B. _score2
    5. A. totalAmount