JavaScript Basics Quiz

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Question 1/15

How can you add a comment in JavaScript?

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Question 2/15

What does "const" declare in JavaScript?

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Question 3/15

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

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Question 4/15

Which one of these is an Arrow Function syntax?

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Question 5/15

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

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Question 6/15

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

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Question 7/15

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

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Question 8/15

Which of the following is a string method in JavaScript?

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Question 9/15

What does "NaN" stand for in JavaScript?

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Question 10/15

What is the output when you execute the following code?
console.log(typeof 42);

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Question 11/15

When the following code is executed, what will the value of the expression be?
3 == '3'

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Question 12/15

What will the following code output?
var fruits = ['Apple', 'Banana', 'Mango'];
console.log(fruits[1]);

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Question 13/15

Which of the following data types exists in JavaScript?

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Question 14/15

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

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Question 15/15

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

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Your Answers

Question 1/15
😊 Your answer was correct 🙁 Your answer was incorrect
How can you add a comment in JavaScript?

Available answers

In JavaScript, comments start with
//
for single-line comments or
/* ... */
for multi-line comments.
Question 2/15
😊 Your answer was correct 🙁 Your answer was incorrect
What does "const" declare in JavaScript?

Available answers

const
declares a variable that is read-only after initialization, meaning it cannot be reassigned.
Question 3/15
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What method is used to add new elements to the end of an array?

Available answers

The
push()
method adds one or more elements to the end of an array.
Question 4/15
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Which one of these is an Arrow Function syntax?

Available answers

An Arrow Function does not use the
function
keyword and looks like
(x, y) => x + y
.
Question 5/15
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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 6/15
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Which of the following will write "Hello World!" to the console?

Available answers

The function
console.log()
is used to output messages to the web console in JavaScript.
Question 7/15
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Which method can be used to convert a JSON string into a JavaScript object?

Available answers

The
JSON.parse()
method is used to convert a JSON string into a JavaScript object.
Question 8/15
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Which of the following is a string method in JavaScript?

Available answers

The
toUpperCase()
method converts a string to uppercase letters.
Question 9/15
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What does "NaN" stand for in JavaScript?

Available answers

NaN
stands for "Not-a-Number", indicating a value that is not a legal number.
Question 10/15
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What is the output when you execute the following code?
console.log(typeof 42);

Available answers

The
typeof
operator returns
'number'
for numerical literals like
42
.
Question 11/15
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When the following code is executed, what will the value of the expression be?
3 == '3'

Available answers

The
==
operator checks for equality with type coercion. Hence
3 == '3'
is
true
.
Question 12/15
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What will the following code output?
var fruits = ['Apple', 'Banana', 'Mango'];
console.log(fruits[1]);

Available answers

Arrays in JavaScript are zero-indexed, so
fruits[1]
contains
'Banana'
.
Question 13/15
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Which of the following data types exists in JavaScript?

Available answers

JavaScript supports data types such as
String, Number, Boolean, Object
, but not specific types like
Character
or
Tuple
.
Question 14/15
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What will the following expression return: Boolean(0);
Boolean(0);

Available answers

The expression
Boolean(0)
returns
false
because
0
is considered a "falsy" value in JavaScript.
Question 15/15
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What is a typical use case for the "isNaN()" function?

Available answers

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