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Different JavaScript Questions and Answers

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(1)Is the following a valid variable definition? var 100apples

No

Yes

Answer:-No

(2)You want to create an alert. Select the correct one

alert('goodbye");

alert('he said "goodbye" ');

alert("goodbye');

Answer:-alert('he said "goodbye" ');

(3)JavaScript has to called inside ________ tags

Either in body or head

head

body

script

Answer:-script

(4)Is the following a valid variable assignment var product cost = 3.45;

No. There should be no space in the variable name

No. Floating numbers are not allowed

Yes. It is valid

Answer:-No. There should be no space in the variable name

(5)Which of the following are not valid in JavaScript?

"My name is "Harry" "

"My name is Harry"

My name is Harry'

"My name is 'Harry' "

Answer:-"My name is "Harry" "

(6)Code A: var x = 10; y = --x + 1;

alert(y);

Code B: var x = 10;

y = x-- + 1;

alert(y);

What is the output for code A and B?

10,11

10,10

11,10

11,11

Answer:-10,11

(7)What is true about variables

7Wonders is a valid variable name to give

% is a valid first character for variable name

Variables are case sensitive

^US is a valid variable name

Answer:-Variables are case sensitive

(8)Select the statement that has correct JavaScript syntax

document.write("text")

alert stop ;

console.log("text");

Answer:-console.log("text");

(9)To display whether a value is a number or not, ____ is used

isNan

NaN

undefined

isundefined

Answer:-isNan

(10)isNan function returns ______ if the argument is not a number otherwise it is ______

False/True

False/False

True / False

True / True

Answer:-True / False

(11)Multiple variables can be created and initialized in a single JavaScript statement

False

True

Answer:-True

(12)What option would you specify when inserting code in a web page? script type="____"

text/language

JavaScript/text

text/JavaScript

Answer:-text/JavaScript

(13)What is the ideal place to load the external JavaScript file in your HTML document

Towards the beginning of the body to load the page along with the JavaScript code

Towards the end of the body to increase the performance of the webpage

Anywhere within the body is good enough

Answer:-Towards the end of the body to increase the performance of the webpage

(14)Which statement will return the value false?

var result = 20 < 50;

var result = 30 >= 30;

var result = (20 === "20") && (50 < 30);

Answer:-var result = (20 === "20") && (50 < 30);

(15)What is the value of C? var a = 100; var b = "10"; var c = a + b;

10010

110

None

10100

Answer:-10010

(16)___________ is a pretest loop that will execute until the value of z equals 10

while (z >10) { z--; }

do { ++z; } while (z < 10);

for (var z= 1; z < 10; z++) { alert (z); }

Answer:-while (z >10) { z--; }

(17)____ allows you to loop through a block of code as long as the specified condition is true.

Tag

While

For

Answer:-While

(18)____ is used to exit a loop early.

Break

Alert

Exit

Continue

Answer:-Break

(19)Can arrays in JavaScript be extended?

Yes, they can be

No, they cannot be

May be, they can be extended conditionally

Answer:-Yes, they can be

(20)In multidimensional array mySubject, which of the following will allow assigning the value 100 in position 5 of the third

mySubject array?

mySubject[3][4] = 100

mySubject[5][3] = 100

mySubject[4][2] = 100

mySubject[2][4] = 100

mySubject[3][5] = 100

Answer:-mySubject[2][4] = 100

(21)Which is the correct way to create an array in JavaScript? I) var myProg = []; II) var myArray = ["C","Java","C++","Python"];

III) var myProg = new Array();

I, III

II, III

I, II

I, II & III

Answer:-I, II & III

(22)In JavaScript, object is a container of properties and functions. Properties are identified by ____ and behavior is identified by

_____

variables, functions

attributes, functions

attributes, variables

functions, variables

Answer:-variables, functions

(23)To retrieve the day of the month from the Date object, which is the code to select?

var date_obj = new Date(2016,1,1);

month_date = date_obj.toDateString();

month_day = date_obj.getDay();

month_date = date_obj.getMonth();

var month_day = date_obj.getDate();

Answer:-var month_day = date_obj.getDate();

(24)What is true about array

Can have combination of data types in a single array list

Must have same data types for array list

Answer:-Can have combination of data types in a single array list

(25)FIbonacci Series Program

function fibonacciSequence(input)

{

var a=0;b=1;c=0;

var array1=[0,1];

for(var i=2;i<=input;i++)

{

c=a+b;

a=b;

b=c;

array1.push(c)

}

return array1;

}

Above code is true ---

Above code is incorrect

Answer:-True

(26) What is true about functions : I) Functions are objects II) Can be assigned to a variable III) Can be anonymous IV) Return value

type has to be defined in function declaration

I, II

I, II, III

I, II, III, IV

I, II, IV

Answer:-I, II, III

(27)What is the output you get for the following code?

(function()

{

return typeof arguments; })

();

undefined

array

arguments

object

Answer:-object

(28)var i = 1; if (function f(){}) { i += typeof f; } x;

1

undefined

Nan

Error

Answer:-undefined

(29)What is the output for the following code

(function f(){

function f(){

return 1; }

return f();

function f()

{ return 2; } })();

NaN

1

2

Error

Answer:-2

(30)_____ is an function contained within an object

Object

None of the options

Function

Method

Answer:-Method

(31)Which of the following regarding scope is true?

Variables that have a local scope are only visible in the function in which they are declared

Function parameters are visible in the function in which they are used

Data that is stored in a variable when a function is called is never cleared out

All variables you use in your program have to be declared as global variables

Answer:-Variables that have a local scope are only visible in the function in which they are declared

(32)Function in JavaScript is an object. True or False ?

False

True

Answer:-True

(33)Anonymous functions can be created in JavaScript. What do anonymous function do?

Overwrite variables that are to be kept updated

Process a variable before passing it on to another function

Automatically define the scope of a value inside a parameter

Answer:-Process a variable before passing it on to another function

(34)What is the output of the following expression?

function multi(x,y) {

var c = x*y;

}

multi(20,3);

20

60

3

Nothing

Answer:-Nothing

(35)Object's properties are similar to variables and methods are similar to

Conditionals

Properties

Functions

Operators

Answer:-Functions

(36)What is the output for the following

function test(x) {

while(x < 5)

{ x++; }

return x; }

alert(test(2));

6

3

2

5

Answer:-5

(37)function multi(a,b) { var ans = a * b; return ans; } var c = _________

multi(15,2);

multi 15, 2;

multi();

Answer:-multi(15,2);

(38)What is the output you get for the following code?

(function()

{

return typeof arguments; })

();

arguments

array

object

undefined

Answer:-object

(39)Which statement about the name and id attributes of form fields is false?

It is customary to give form fields both attributes, with the same value if possible.

The id attribute is what is sent when the form is submitted.

The name attribute can be used to access the field using getElementsByName().

Either attribute may be omitted if it is unused.

Answer:-The id attribute is what is sent when the form is submitted.

(40)Document object is part of ____ object

System

Tree

Window

Answer:-Window

(41)Using HTML button tag, JavaScript command can be executed by using ____ function

"alert('Button1');

"alert(Button1);"

"alert('Button1');"

"alert('Button");"

Answer:-"alert('Button1');

(42)By modifying the DOM, the contents on the page also gets modified

True

False

Answer:-True

(43)For any structured document, _____ defines a standard set of objects

XML DOM

HTML DOM

Core DOM

Answer:-Core DOM

(44)Which statement accesses HTML classes?

getElementsByClassName

class.name

getElementById

Answer:-getElementsByClassName

(45)How many 'onload' events can be written in a page

2

1

None

Many

Answer:-1

(46)Which is the most preferred way of handling events?

Referencing an element with the event and assign a function as a value

Register a listener to an element

Writing the JavaScript as an attribute to an element

Answer:-Register a listener to an element

(47)AJAX requests can support data transfer in ______ format

None of the options

JSON

XML

Any

Answer:-Any

(48)_____ object is used to make calls and request data from server

GET

XML

XMLHttpRequest

Answer:-XMLHttpRequest

(48)The data from the AJAX request is usually in XML. True or False?

False

True

Answer:-False

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