Loading... Login Loading... Register

JavaScript Basics Quiz

Want to learn more than this quiz offers you? Have a look at my Frontend web development courses.

Create an account and save your quiz results

Login and save your results

First Name *

Last Name *

Email *

Password *

Confirm Password *

I agree to the Terms of Service & Privacy Policy.

Add me to your newsletter.

Question 1/15

Which operator is used to assign a value to a variable?

Select your answer

===

Question 2/15

What will the following code output?

var fruits = ['Apple', 'Banana', 'Mango'];
console.log(fruits[1]);

Select your answer

fruits

Apple

Mango

Banana

Question 3/15

What does the "alert()" function do in JavaScript?

Select your answer

Logs a message to the console.

Displays an alert box with a message and an OK button.

Writes a message to the HTML document.

Displays an alert box with a Yes/No button.

Question 4/15

Which method can be used to convert a JSON string into a JavaScript object?

Select your answer

JSON.stringify()

JSON.toString()

JSON.convert()

JSON.parse()

Question 5/15

What does "const" declare in JavaScript?

Select your answer

A type-checked variable.

A variable that can be changed later.

A variable whose value is synced to the cloud.

A read-only reference to a value.

Question 6/15

How do you find the number with the highest value of x and y?

Math.max(x, y);

Select your answer

Math.max(x, y)

Math.ceil(x, y)

ceil(x, y)

top(x, y)

Question 7/15

What does "NaN" stand for in JavaScript?

Select your answer

Next-as-Number

Null-and-Nothing

Not-a-Number

Numerical-and-Null

Question 8/15

Which of these is not a reserved word in JavaScript?

Select your answer

program

throw

default

switch

Question 9/15

When the following code is executed, what will the value of the expression be?

3 == '3'

Select your answer

false

true

NaN

undefined

Question 10/15

What is the output when you execute the following code?

console.log(typeof 42);

Select your answer

integer

string

object

number

Question 11/15

Which of the following will write "Hello World!" to the console?

Select your answer

print('Hello World!');

log('Hello World!');

write('Hello World!');

console.log('Hello World!');

Question 12/15

Which of the following is a string method in JavaScript?

Select your answer

toUpperCase()

getElementById()

setTimeout()

parseInt()

Question 13/15

How do you round 7.25 to the nearest integer in JavaScript?

Math.round(7.25);

Select your answer

Math.round(7.25)

Math.rnd(7.25)

rnd(7.25)

round(7.25)

Question 14/15

What is the output of the following JavaScript code?

var x = 10;
x += 5;
console.log(x);

Select your answer

Question 15/15

What will the following expression return: Boolean(0);

Boolean(0);

Select your answer

false

true

null

undefined

Your Results

You did not answer any questions correctly.

Your Answers

Question 1/15

😊 Your answer was correct 🙁 Your answer was incorrect

Which operator is used to assign a value to a variable?

Available answers

===

The assignment operator in JavaScript is

, used to assign values to variables.

Question 2/15

😊 Your answer was correct 🙁 Your answer was incorrect

What will the following code output?

var fruits = ['Apple', 'Banana', 'Mango'];
console.log(fruits[1]);

Available answers

fruits

Apple

Mango

Banana

Arrays in JavaScript are zero-indexed, so

fruits[1]

contains

'Banana'

Question 3/15

😊 Your answer was correct 🙁 Your answer was incorrect

What does the "alert()" function do in JavaScript?

Available answers

Logs a message to the console.

Displays an alert box with a message and an OK button.

Writes a message to the HTML document.

Displays an alert box with a Yes/No button.

The

alert()

function displays an alert box containing a specified message and an OK button.

Question 4/15

😊 Your answer was correct 🙁 Your answer was incorrect

Which method can be used to convert a JSON string into a JavaScript object?

Available answers

JSON.stringify()

JSON.toString()

JSON.convert()

JSON.parse()

The

JSON.parse()

method is used to convert a JSON string into a JavaScript object.

Question 5/15

😊 Your answer was correct 🙁 Your answer was incorrect

What does "const" declare in JavaScript?

Available answers

A type-checked variable.

A variable that can be changed later.

A variable whose value is synced to the cloud.

A read-only reference to a value.

const

declares a variable that is read-only after initialization, meaning it cannot be reassigned.

Question 6/15

😊 Your answer was correct 🙁 Your answer was incorrect

How do you find the number with the highest value of x and y?

Math.max(x, y);

Available answers

Math.max(x, y)

Math.ceil(x, y)

ceil(x, y)

top(x, y)

The function

Math.max()

is used to find the highest value among its parameters.

Question 7/15

😊 Your answer was correct 🙁 Your answer was incorrect

What does "NaN" stand for in JavaScript?

Available answers

Next-as-Number

Null-and-Nothing

Not-a-Number

Numerical-and-Null

NaN

stands for "Not-a-Number", indicating a value that is not a legal number.

Question 8/15

😊 Your answer was correct 🙁 Your answer was incorrect

Which of these is not a reserved word in JavaScript?

Available answers

program

throw

default

switch

The word

program

is not a reserved keyword in JavaScript, unlike

switch, throw, default

Question 9/15

😊 Your answer was correct 🙁 Your answer was incorrect

When the following code is executed, what will the value of the expression be?

3 == '3'

Available answers

false

true

NaN

undefined

The

==

operator checks for equality with type coercion. Hence

3 == '3'

true

Question 10/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the output when you execute the following code?

console.log(typeof 42);

Available answers

integer

string

object

number

The

typeof

operator returns

'number'

for numerical literals like

Question 11/15

😊 Your answer was correct 🙁 Your answer was incorrect

Which of the following will write "Hello World!" to the console?

Available answers

print('Hello World!');

log('Hello World!');

write('Hello World!');

console.log('Hello World!');

The function

console.log()

is used to output messages to the web console in JavaScript.

Question 12/15

😊 Your answer was correct 🙁 Your answer was incorrect

Which of the following is a string method in JavaScript?

Available answers

toUpperCase()

getElementById()

setTimeout()

parseInt()

The

toUpperCase()

method converts a string to uppercase letters.

Question 13/15

😊 Your answer was correct 🙁 Your answer was incorrect

How do you round 7.25 to the nearest integer in JavaScript?

Math.round(7.25);

Available answers

Math.round(7.25)

Math.rnd(7.25)

rnd(7.25)

round(7.25)

To round a number in JavaScript, use

Math.round()

Question 14/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the output of the following JavaScript code?

var x = 10;
x += 5;
console.log(x);

Available answers

The code uses

+=

to add

, giving

Question 15/15

😊 Your answer was correct 🙁 Your answer was incorrect

What will the following expression return: Boolean(0);

Boolean(0);

Available answers

false

true

null

undefined

The expression

Boolean(0)

returns

false

because

is considered a "falsy" value in JavaScript.