Javascript - Syntax

1. What is the purpose of the semicolon in JavaScript?

To indicate the end of a statement

To separate HTML and JavaScript code

To define a block of code

To concatenate strings

Difficulty

2000

low

2. How do you declare a constant variable in JavaScript?

var myVar = value;

const myVar = value;

let myVar = value;

constant myVar = value;

Difficulty

2200

medium

3. What is the correct way to comment multiple lines in JavaScript?

// comment

/* comment */

** comment **

Difficulty

2200

medium

4. How do you check if a variable is of a certain type in JavaScript?

typeof variable

checkType(variable)

variable.getType()

typeOf(variable)

Difficulty

2400

medium

5. Which of the following is the correct way to create an array in JavaScript?

var myArray = [];

array myArray = [];

let myArray = new Array();

myArray = {};

Difficulty

2800

medium

6. How do you concatenate two strings in JavaScript?

string1.join(string2)

string1.concat(string2)

string1 + string2

concat(string1, string2)

Difficulty

2600

medium

7. What is the purpose of the "switch" statement in JavaScript?

To define a loop

To handle errors

To execute a block of code based on different cases

To create a new variable

Difficulty

3000

medium

8. What is the purpose of the "typeof" operator in JavaScript?

To check if a variable is defined

To determine the type of a variable or expression

To create a new variable

To concatenate strings

Difficulty

3000

medium

9. What is the purpose of the "NaN" value in JavaScript?

Not a Null

Not a Number

No Assignment Needed

Null and None

Difficulty

3400

high

10. How can you escape special characters in a string in JavaScript?

Using backslashes (\)

Using single quotes (')

Using double quotes (")

Special characters cannot be escaped

Difficulty

2800

medium

11. Which operator is used for exponentiation in JavaScript?

Difficulty

2700

medium

12. What is the purpose of the "break" statement in a loop in JavaScript?

To skip the next iteration of the loop

To terminate the loop and exit it

To continue to the next iteration of the loop

To restart the loop from the beginning

Difficulty

2800

medium

13. What is the purpose of the "this" keyword in JavaScript?

Refers to the current function

Refers to the current object

Declares a new variable

Represents the global scope

Difficulty

3000

medium

14. How can you convert a string to an integer in JavaScript?

toInteger()

parseInt()

stringToInteger()

convertToInt()

Difficulty

2600

medium

15. What is the role of the "try...catch" statement in JavaScript?

To create a loop

To handle exceptions and errors

To define a function

To initiate an asynchronous operation

Difficulty

4200

very high

16. Which of the following one is the property of the primary expression:

Contains only keywords

basic expressions containing all necessary functions

contains variable references alone

stand-alone expressions

Difficulty

3200

high

17. Which one of the following is not a keyword:

with

debugger

use strict

Difficulty

2400

medium

18. Which one of the following is not considered as "statement" in the JavaScript?

use strict

debugger

with

Difficulty

2400

medium

19. Which of the following is the correct JavaScript syntax to access the element using HTML code?

getElement ("availablecourse").innerHTML = "See the list of availablecourse";

getElementById ("availablecourse").innerHTML = "See the list of availablecourse";

document.getElementById ("availablecourse").innerHTML = "See the list of availablecourse";

documentId("availablecourse").innerHTML = See the list of availablecourse;

Difficulty

2600

medium

20. Which of the following syntax can be used to write "Hello World" in an alert box?

alertBox("Hello World");

msgBox("Hello World");

alert("Hello World");

msg("Hello World");

Difficulty

1800

low

Syntax

Want to challenge your knowledge?

Question Bank

1. What is the purpose of the semicolon in JavaScript?

2. How do you declare a constant variable in JavaScript?

3. What is the correct way to comment multiple lines in JavaScript?

4. How do you check if a variable is of a certain type in JavaScript?

5. Which of the following is the correct way to create an array in JavaScript?

6. How do you concatenate two strings in JavaScript?

7. What is the purpose of the "switch" statement in JavaScript?

8. What is the purpose of the "typeof" operator in JavaScript?

9. What is the purpose of the "NaN" value in JavaScript?

10. How can you escape special characters in a string in JavaScript?

11. Which operator is used for exponentiation in JavaScript?

12. What is the purpose of the "break" statement in a loop in JavaScript?

13. What is the purpose of the "this" keyword in JavaScript?

14. How can you convert a string to an integer in JavaScript?

15. What is the role of the "try...catch" statement in JavaScript?

16. Which of the following one is the property of the primary expression:

17. Which one of the following is not a keyword:

18. Which one of the following is not considered as "statement" in the JavaScript?

19. Which of the following is the correct JavaScript syntax to access the element using HTML code?

20. Which of the following syntax can be used to write "Hello World" in an alert box?

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