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JavaScript Basics Quiz

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Question 1/15

What does "NaN" stand for in JavaScript?

Select your answer

Next-as-Number

Not-a-Number

Numerical-and-Null

Null-and-Nothing

Question 2/15

What will the value of "x" be after the code is run?

let x = 5;
x = x * 2;

Select your answer

undefined

Question 3/15

How can you add a comment in JavaScript?

Select your answer

&& This is a comment

# This is a comment

// This is a comment

Question 4/15

In JavaScript, what will '2' + 2 evaluate to?

Select your answer

'22'

'4'

undefined

Question 5/15

What is the output of the following JavaScript code?

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

Select your answer

Question 6/15

What is a typical use case for the "isNaN()" function?

Select your answer

To append a string to a number.

To check if a value is not a number.

To find the maximum number.

To convert a value to a string.

Question 7/15

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

Select your answer

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

Displays an alert box with a Yes/No button.

Writes a message to the HTML document.

Logs a message to the console.

Question 8/15

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

Math.round(7.25);

Select your answer

round(7.25)

rnd(7.25)

Math.rnd(7.25)

Math.round(7.25)

Question 9/15

How do you write an "if" statement in JavaScript to execute some code if "i" is equal to 5?

if (i === 5) {
    // code to execute
}

Select your answer

if i == 5 then

if i = 5

if (i === 5)

if i = 5 then

Question 10/15

How do you create a function in JavaScript?

function myFunction() {
    // code here
}

Select your answer

function:myFunction()

create function myFunction()

new Function myFunction()

function myFunction()

Question 11/15

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

3 == '3'

Select your answer

true

undefined

NaN

false

Question 12/15

What is the correct way to declare a variable in JavaScript?

Select your answer

var myVariable;

declare myVariable;

variable myVariable;

v myVariable;

Question 13/15

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

Boolean(0);

Select your answer

true

null

undefined

false

Question 14/15

What is the correct syntax for referring to an external JavaScript file called 'app.js'?

Select your answer

Question 15/15

What method is used to add new elements to the end of an array?

Select your answer

append()

add()

insert()

push()

Your Results

You did not answer any questions correctly.

Your Answers

Question 1/15

😊 Your answer was correct 🙁 Your answer was incorrect

What does "NaN" stand for in JavaScript?

Available answers

Next-as-Number

Not-a-Number

Numerical-and-Null

Null-and-Nothing

NaN

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

Question 2/15

😊 Your answer was correct 🙁 Your answer was incorrect

What will the value of "x" be after the code is run?

let x = 5;
x = x * 2;

Available answers

undefined

The operation

x = x * 2

assigns the result of

5 * 2

, which is

Question 3/15

😊 Your answer was correct 🙁 Your answer was incorrect

How can you add a comment in JavaScript?

Available answers

&& This is a comment

# This is a comment

// This is a comment

In JavaScript, comments start with

//

for single-line comments or

/* ... */

for multi-line comments.

Question 4/15

😊 Your answer was correct 🙁 Your answer was incorrect

In JavaScript, what will '2' + 2 evaluate to?

Available answers

'22'

'4'

undefined

In JavaScript, the expression

'2' + 2

results in the string '22' due to string concatenation.

Question 5/15

😊 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 6/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is a typical use case for the "isNaN()" function?

Available answers

To append a string to a number.

To check if a value is not a number.

To find the maximum number.

To convert a value to a string.

The

isNaN()

function checks if a value is NaN (Not-a-Number).

Question 7/15

😊 Your answer was correct 🙁 Your answer was incorrect

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

Available answers

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

Displays an alert box with a Yes/No button.

Writes a message to the HTML document.

Logs a message to the console.

The

alert()

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

Question 8/15

😊 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

round(7.25)

rnd(7.25)

Math.rnd(7.25)

Math.round(7.25)

To round a number in JavaScript, use

Math.round()

Question 9/15

😊 Your answer was correct 🙁 Your answer was incorrect

How do you write an "if" statement in JavaScript to execute some code if "i" is equal to 5?

if (i === 5) {
    // code to execute
}

Available answers

if i == 5 then

if i = 5

if (i === 5)

if i = 5 then

The syntax for an "if" statement in JavaScript to check for equality is:

if (i === 5) { /* code */ }

Question 10/15

😊 Your answer was correct 🙁 Your answer was incorrect

How do you create a function in JavaScript?

function myFunction() {
    // code here
}

Available answers

function:myFunction()

create function myFunction()

new Function myFunction()

function myFunction()

To define a function in JavaScript, use the syntax:

function myFunction() { /* code */ }

Question 11/15

😊 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

true

undefined

NaN

false

The

==

operator checks for equality with type coercion. Hence

3 == '3'

true

Question 12/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the correct way to declare a variable in JavaScript?

Available answers

var myVariable;

declare myVariable;

variable myVariable;

v myVariable;

In JavaScript, you declare a variable using the

var

let

, or

const

keyword, such as

var myVariable;

Question 13/15

😊 Your answer was correct 🙁 Your answer was incorrect

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

Boolean(0);

Available answers

true

null

undefined

false

The expression

Boolean(0)

returns

false

because

is considered a "falsy" value in JavaScript.

Question 14/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the correct syntax for referring to an external JavaScript file called 'app.js'?

Available answers

To include an external JavaScript file, you use the

<script src='app.js'></script>

syntax.

Question 15/15

😊 Your answer was correct 🙁 Your answer was incorrect

What method is used to add new elements to the end of an array?

Available answers

append()

add()

insert()

push()

The

push()

method adds one or more elements to the end of an array.