CSE326 Unit 4: JavaScript Application Development - MCQ Practice | B. Tech. CSE

1 $Which HTML tag is used to embed JavaScript code inside a webpage?$

A.

<js>

B.

<javascript>

C.

<script>

D.

<code>

2 $Which attribute of the <script> tag is used to include an external JavaScript file?$

A.

link

B.

rel

C.

href

D.

src

3 $Where is the correct place to insert a JavaScript in an HTML document?$

A.

The <head> section

B.

Both the <head> section and the <body> section

C.

The <body> section

D.

The <footer> section

4 $What is the correct file extension for an external JavaScript file?$

A.

.html

B.

.js

C.

.java

D.

.script

5 $How do you write 'Hello World' in an alert box?$

A.

alert('Hello World');

B.

alertBox('Hello World');

C.

msgBox('Hello World');

D.

msg('Hello World');

6 $Which keyword is used to declare a variable that cannot be reassigned?$

A.

var

B.

const

C.

let

D.

static

7 $What is the scope of a variable declared with 'let' inside a block?$

A.

Block scope

B.

Module scope

C.

Function scope

D.

Global scope

8 $Which operator is used to check both value and type equality?$

A.

!=

B.

==

C.

=

D.

===

9 $What is the result of the expression: '5' + 3?$

A.

8

B.

NaN

C.

53

D.

Error

10 $Which function is used to get input from the user?$

A.

prompt()

B.

alert()

C.

input()

D.

confirm()

11 $What does the confirm() method return?$

A.

Object

B.

String

C.

Integer

D.

Boolean

12 $How does a 'while' loop start?$

A.

while (i <= 10; i++)

B.

while (i <= 10)

C.

until (i <= 10)

D.

while i = 1 to 10

13 $Which statement is used to stop a loop completely?$

A.

break

B.

return

C.

continue

D.

stop

14 $What is the purpose of the 'continue' statement?$

A.

Restarts the loop

B.

Stops the loop execution

C.

Exits the function

D.

Skips the current iteration

15 $Which loop is guaranteed to execute at least once?$

A.

foreach

B.

do...while

C.

for

D.

while

16 $How do you write an IF statement in JavaScript?$

A.

if i = 5

B.

if i = 5 then

C.

if (i == 5)

D.

if i == 5 then

17 $How do you write an IF statement for executing some code if 'i' is NOT equal to 5?$

A.

if i not 5

B.

if (i <> 5)

C.

if i =! 5 then

D.

if (i != 5)

18 $Which symbol is used for single-line comments in JavaScript?$

A.

**

B.

/ /

C.

//

D.

<!-- -->

19 $What is the correct syntax for referring to an external script called 'app.js'?$

A.

<script href='app.js'>

B.

<script file='app.js'>

C.

<script src='app.js'>

D.

<script name='app.js'>

20 $How do you create a JavaScript object?$

A.

var obj = ();

B.

var obj = [];

C.

var obj = {};

D.

var obj = <>;

21 $Given: var person = {firstName:'John', lastName:'Doe'}; How do you access the lastName?$

A.

person[lastName]

B.

person->lastName

C.

person.lastName

D.

person::lastName

22 $Which keyword is used to define a variable in JavaScript (ES5 legacy)?$

A.

string

B.

dim

C.

int

D.

var

23 $What is the correct way to write a JavaScript array?$

A.

var colors = 'red', 'green', 'blue'

B.

var colors = 1 = ('red'), 2 = ('green'), 3 = ('blue')

C.

var colors = ['red', 'green', 'blue']

D.

var colors = (1:'red', 2:'green', 3:'blue')

24 $Inside which HTML element do we put the JavaScript?$

A.

<script>

B.

<scripting>

C.

<js>

D.

<javascript>

25 $What will be the output of: typeof 'Hello'?$

A.

String

B.

text

C.

string

D.

object

26 $Which statement serves as the fall-back in a 'switch' statement?$

A.

else

B.

default

C.

break

D.

case

27 $What is the correct syntax for a 'for' loop?$

A.

for (i = 0; i <= 5; i++)

B.

for (i = 0; i <= 5)

C.

for i = 1 to 5

D.

for (i <= 5; i++)

28 $How can you add a comment that has more than one line?$

A.

<!-- This is a comment -->

B.

// This is a comment //

C.

/ This is a comment /

D.

This is a comment

29 $Which operator is used to assign a value to a variable?$

A.

*

B.

==

C.

-

D.

=

30 $What is the value of 'x' after: var x = 10; x += 5;$

A.

5

B.

15

C.

10

D.

Error

31 $Which keyword identifies a block of code to be executed if a specified condition is false?$

A.

break

B.

then

C.

stop

D.

else

32 $In an object method, what does 'this' refer to?$

A.

The function itself

B.

The global object

C.

The owner object

D.

The variable name

33 $Which logical operator represents 'OR'?$

A.

&

B.

!

C.

||

D.

&&

34 $What is the correct way to check if a variable 'car' is undefined?$

A.

if (car is undefined)

B.

if (car == null)

C.

if (car === undefined)

D.

if (typeof car == 'undefined')

35 $Which of the following is NOT a valid JavaScript variable name?$

A.

_myVar

B.

2myVar

C.

myVar2

D.

$myVar

36 $What syntax is used to access a method 'start' of an object 'engine'?$

A.

call engine.start

B.

engine.start()

C.

engine->start()

D.

engine['start']

37 $What happens if you redeclare a variable using 'let' in the same scope?$

A.

It creates a new variable

B.

It overwrites the previous value

C.

It causes a SyntaxError

D.

Nothing happens

38 $Which property is used to find the length of a string?$

A.

length

B.

len

C.

count

D.

size

39 $What is the output of Boolean(10 > 9)?$

A.

false

B.

undefined

C.

NaN

D.

true

40 $Which is the ternary operator?$

A.

||

B.

?:

C.

??

D.

&&

41 $What keyword defines a switch case block?$

A.

if

B.

when

C.

option

D.

case

42 $How do you delete a property from a JavaScript object?$

A.

remove object.property

B.

delete object.property

C.

object.property = null

D.

clear object.property

43 $Which popup box returns null if the user clicks 'Cancel'?$

A.

confirm

B.

prompt

C.

alert

D.

message

44 $What is Hoisting in JavaScript?$

A.

Moving declarations to the top

B.

Looping efficiently

C.

Moving initializations to the top

D.

Deleting unused variables

45 $Which of the following is a valid const declaration?$

A.

const PI;

B.

const PI = 3.14;

C.

const 3.14 = PI;

D.

const PI = 3.14; PI = 3.14159;

46 $What loop is best suited for iterating over the properties of an object?$

A.

for...in

B.

while

C.

do...while

D.

for

47 $Which symbol is used for the modulus (remainder) operator?$

A.

&

B.

*

C.

/

D.

%

48 $If x = 10 and y = '10', what is the result of x == y?$

A.

true

B.

undefined

C.

false

D.

NaN

49 $If x = 10 and y = '10', what is the result of x === y?$

A.

undefined

B.

false

C.

true

D.

NaN

50 $Which global object do alert(), confirm(), and prompt() belong to?$

A.

console

B.

window

C.

html

D.

document

Unit 4: JavaScript Application Development - Practice Quiz

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