Javascript

Question 1

1. HTML to define the _______
2. CSS to specify the _______
3. JavaScript to program the _______

Answer 1

1. content of web pages
2. layout of web pages
3. behavior of web pages

Question 2

Javascript Syntax:

Answer 2

p id=”demo”

<script>
document.getElementById("demo").innerHTML = "My First JavaScript";
</script>

Question 3

p id=”_____”

button type=”button” _______=”myFunction()”

<_____>
function _____() {
document.getElementById(“demo”)._________= “Paragraph changed.”;
}
</_____>

Answer 3

p id=”demo”

button type=”button” onclick=”myFunction()”

<script>
function myFunction() {
  document.getElementById("demo").innerHTML = "Paragraph changed.";
}
</script>

Question 4

External JavaScript:
Scripts can also be placed in external files:

Answer 4

script src=”myScript.js” script

Question 5

To access an HTML element, JavaScript can use the __________ method.

Answer 5

document.getElementById(id)

Question 6

The innerHTML property defines the ___________

Answer 6

HTML content

Question 7

window.alert() use:

Answer 7

You can use an alert box to display data.
You can skip the window keyword. It is Optional.
alert()

Question 8

For debugging purposes, you can call the __________ method in the browser to display data.

Answer 8

console.log()

Question 9

How to print the content of the current window in javascript?

Answer 9

button onclick=”window.print()”

Question 10

JavaScript uses the keywords ________ to declare variables.

Answer 10

var, let and const
let x;
x = 6;

Question 11

Code after double slashes ___ or between________ is treated as a comment.

Answer 11

//
/* and */

Question 12

__________ are not allowed in JavaScript. They are reserved for subtractions.

Answer 12

Hyphens

Question 13

‘Let’ keywords cannot be _____

Answer 13

Redeclared

Question 14

Variables defined with ___ can be redeclared.

Answer 14

var

Question 15

javascript variable declaration syntax:

Answer 15

p id=”demo”> /p

script
let person = “John Doe”, carName = “Volvo”, price = 200;
document.getElementById(“demo”).innerHTML = carName;
/script

Question 16

A variable declared without a value will have the value ______

Answer 16

undefined

Question 17

let x = 2 + 3 + “5”;

Ans: ____

Answer 17

55
5 + “5” is string text so it will concatenate

Question 18

Variables declared with let have ______, must be Declared before use and cannot be Redeclared in the same scope.

Answer 18

Block Scope
{
let x = 2;
}
// x can NOT be used here

Question 19

Hoisting: Variables defined with var are hoisted to the top and can be initialized at any time.

Answer 19

Meaning: You can use the variable before it is declared:
carName = “Volvo”;
document.getElementById(“demo”).innerHTML = carName;
var carName;

Question 20

JavaScript has 8 Datatypes

Answer 20

String
Number
Bigint
Boolean
Undefined
Null
Symbol
Object

Question 21

JavaScript _____ operator to find the type of a JavaScript variable.

Answer 21

typeof
typeof “John Doe”; //string
typeof 314 // Returns “number”

Question 22

Exponential Notation
let y = 123e5; // _________
let z = 123e-5; // _______

Answer 22

12300000
0.00123

Question 23

All JavaScript numbers are stored in a ____ floating-point format.

Answer 23

64-bit

Question 24

JavaScript BigInt is a new datatype (ES2020) that can be used to store integer values that ____________ by a normal JavaScript Number.

Answer 24

are too big to be represented

Question 25

A JavaScript function is a block of code designed to perform a ___________

Answer 25

particular task.

Question 26

A JavaScript function is defined with the _______ keyword, followed by a _____, followed by _____________.

Answer 26

function
name
parentheses ()
function name(parameter1, parameter2, parameter3) {
// code to be executed
}

Question 27

It is a common practice to declare objects with the ____ keyword.

Answer 27

const

Question 28

In JavaScript, almost “______” is an object.

Answer 28

everything
Objects are objects
Maths are objects
Functions are objects
Dates are objects
Arrays are objects

Question 29

A primitive value is a value that has __________

Answer 29

no properties or methods.
3.14 is a primitive value

Question 30

JavaScript defines 7 types of primitive data types:

Answer 30

string
number
boolean
null
undefined
symbol
bigint

Question 31

Objects are containers for _________

Answer 31

Properties and Methods.