Javascript MCQ Quiz 2023: JavaScript is a dynamic programming language that is used for web development, web applications, game development etc. It allows you to implement dynamic features on web pages that cannot be done with only HTML and CSS. JavaScript is a text-based programming language used both on client-side and server-side and allows you to make web pages interactive. HTML and CSS languages that give structure and style to web pages. Here are the 30 Javascript Multiple choice questions with answers/Javascript MCQ With Answers for Exams are given below.
Table of Contents

1. Questions and Answers for Javascript MCQ Quiz 2023
1. Which of the following option is used as hexadecimal literal beginning?
- 00
- 0x
- 0X
- Both 0x and 0X
Answer: Both 0x and 0X
2. In the JavaScript, which one of the following is not considered as an error________
- Missing of semicolons
- Syntax error
- Division by zero
- Missing of Bracket
Answer: Division by zero
3. When there is an indefinite or an infinite value during an arithmetic computation in a program, then JavaScript prints____________
- Prints an overflow error
- Prints an exception error
- Prints the value as such
- Displays “Infinity”
Answer: Displays “Infinity”
4. Which of the following type of a variable is volatile?
- Dynamic variable
- Mutable variable
- Volatile variable
- Immutable variable
Answer: Dynamic variable
5. Which of the following given functions of the Number Object formats a number with a different number of digits to the right of the decimal?
- toPrecision()
- toFixed()
- toExponential()
- toLocaleString()
Answer: toFixed()
6. Which of the following function of the String object returns the character in the string starting at the specified position via the specified number of characters?
- split()
- slice()
- substr()
- search()
Answer: substr()
7. Which one of the following is the correct way for calling the JavaScript code?
- Triggering Event
- Preprocessor
- Function/Method
- RMI
Answer: Function/Method
8. Which of the following number object function returns the value of the number?
- valueOf()
- toString()
- toLocaleString()
- DtoPrecision()
Answer: valueOf()
9. In JavaScript the x===y statement implies that____________
- Both are equal in the value and data type
- Both are not same at all
- Both are x and y are equal in value only
- Both x and y are equal in value, type and reference address as well
Answer: Both are equal in the value and data type
10. Which of the following variables takes precedence over the others if the names are the same?
- The local element
- Global variable
- The two of the above
- None
Answer: The local element
11. Choose the correct snippet from the following to check if the variable “a” is not equal the “NULL”_______
- if(a!==null)
- if (a!)
- if(a!=null)
- if(a!null)
Answer: if(a!==null)
12. The “function” and ” var” are known as________
- Keywords
- Data types
- Prototypes
- Declaration statements
Answer: Declaration statements
13. Suppose we have a text “human” that we want to convert into string without using the “new” operator. Which is the correct way from the following to do so___________
- String newvariable=”human”
- String(human)
- toString()
- Both human.toString() and String(human)
Answer: Both human.toString() and String(human)
14. In JavaScript, what will be used for calling the function definition expression_______
- Function literal
- Function calling
- Function prototype
- Function declaration
Answer: Function literal
15. Which of the following one is the property of the primary expression_________
- contains variable references alone
- Contains only keywords
- basic expressions containing all necessary functions
- stand-alone expressions
Answer: stand-alone expressions
16. Which one of the following is used for the calling a function or a method in the JavaScript__________
- Invocation expression
- Functional expression
- Property Access Expression
- Primary expression
Answer: Invocation expression
17. When interpreter encounters an empty statements, what it will do_________
- Throws an error
- Prompts to complete the statement
- Shows a warning
- Ignores the statements
Answer: Ignores the statements
18. The “new Point(3,2)”, is a kind of _______ expression
- Invocation Expression
- Primary Expression
- Object Creation Expression
- Constructor Calling Expression
Answer: Object Creation Expression
19. Which one of the following operator is used to check weather a specific property exists or not__________
- in
- exist
- Exists
- within
Answer: in
20. What if we define a “for” loop and it removes one of the properties that has not yet been enumerated?
- The loop will not run at all
- The removed property will be stored in a cache
- That property will be enumerated
- That specific property will not be enumerated
Answer: That specific property will not be enumerated
21. Which one of the following is not a keyword__________
- with
- if
- debugger
- use strict
Answer: use strict
22. Which one of the following is not considered as “statement” in the JavaScript?
- with
- if
- debugger
- use strict
Answer: use strict
23. In JavaScript, what is a block of statement?
- block that contains a single statement
- block that combines a number of statements into a single compound statement
- Conditional block
- both conditional block and a single statement
Answer: block that combines a number of statements into a single compound statement
24. In a case, where the value of the operator is NULL , the typeof returned by the unary operator is__________.
- string
- undefined
- boolean
- object
Answer: object
25. Which one of the following is an ternary operator___________
- +
- ?
- :
- –
Answer: ?
26. Which one of the following also known as Conditional Expression__________
- Switch statement
- Alternative to if-else
- If-then-else statement
- immediate if
Answer: immediate if
27. Which one of the following operator returns false if both values are equal?
- ==
- !==
- !
- &&
Answer: ==
28. “An expression that can legally appear on the left side of an assignment expression.” is a well known explanation for variables, properties of objects, and elements of arrays. They are called_____
- Prototypes
- Properties
- Definition
- Lvalue
Answer: Lvalue
29. What we will get if we compare the “one” with “8” using the less than operator (“one”<8)?
- NaN
- True
- False
- Undefined
Answer: False
30. Which type of JavaScript language is ___
- Object-Based
- Object-Oriented
- Assembly-language
- High-level
Answer: Object-Based
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