JavaScript-Learning

1. Basic JavaScript Syntax

Hello World in JS

console.log("Hello World");

OUTPUT

Hello World

The log( ) function is used to print a value to the console.

Variables

Variables in JS are used to store a value under a name.

Variable Declaration using 'var'

var name = "Avantika";
var age = 21;
console.log(name, age);

OUTPUT

Avantika 21

'var' was an older way of to create variables.
It ignores the block scope.

Variable Declaration using 'let'

let name = "Avantika";
let age = 21;
console.log(name, age);

OUTPUT

Avantika 21

'let' works same as 'var'.

Variable Declaration using 'const'

const name = "Avantika";
const age = 21;
console.log(name, age);

OUTPUT

Avantika 21

'const' is also used to create variables.
It doesn't allow updation of the variable once it is formed.

Data Types

Numbers

let age = 21;
let phone = 12345;
let pi = 3.14159;
console.log(age, phone, pi);

OUTPUT

21 12345 3.14159

Number datatype in JS includes both integers and decimal numbers.

Strings

let name = "Avantika";
let country = "India";
console.log("My name is " + name + " and I live in " + country);

OUTPUT

My name is Avantika and I live in India

String is a combination of characters. enclosed in double-quotes( " " ).

Arrays

let colors = ["red", "blue", "pink", "green"];
console.log(colors);

OUTPUT

["red" , "blue" , "pink" , "green"]

Arrays are combination of multiple values of various data types under a single name.

Boolean

let is_rain = False;
let can_vote = True;
console.log(is_rain, can_vote);

OUTPUT

False True

Boolean consists of only two values - True and False.

Null and undefined

let a;
let b = null;
console.log(a, b);

OUTPUT

undefined null

Null - It represents the intentional absence of a value.
Undefined - It shows that the value is yet to be assigned.

Comparison Operators

let age = 18;

console.log(age == 18); // Is equal to
console.log(age != 18); // Is not equal to
console.log(age > 18); // Is greater than
console.log(age < 18); // Is less than

OUTPUT

True
False
False
False

Loose comparison

let age = 18;
console.log(age == 18);
console.log(age == "18"); // Implicit type conversion takes place

OUTPUT

True
True

Before comparing, Type conversion takes place.

Strict comparison

let age = 18;
console.log(age === 18);
console.log(age === "18"); // no type conversion takes place.

OUTPUT

True
False

No type conversion takes place before comparison.

Type Conversion

Implicit conversion

let age = 18;
console.log(age == 18);
console.log(age == "18"); // Implicit type conversion takes place

OUTPUT

True
True

In this example, type conversion is done by browser, thus it is an Implicit conversion.

Explicit conversion

let age = 20;
console.log(age);

age = "Twenty";
console.log(age);

OUTPUT

20
Twenty

Type conversion done by the user is known as Explicit Type Conversion.

Name		Name	Last commit message	Last commit date
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1_syntax_basics.js		1_syntax_basics.js
2_control_flow.js		2_control_flow.js
3_functions.js		3_functions.js
4_objects.js		4_objects.js
5_DOM.js		5_DOM.js
README.md		README.md
index.html		index.html
playbook.js		playbook.js

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JavaScript-Learning

1. Basic JavaScript Syntax

Hello World in JS

OUTPUT

Variables

Variable Declaration using 'var'

OUTPUT

Variable Declaration using 'let'

OUTPUT

Variable Declaration using 'const'

OUTPUT

Data Types

Numbers

OUTPUT

Strings

OUTPUT

Arrays

OUTPUT

Boolean

OUTPUT

Null and undefined

OUTPUT

Comparison Operators

OUTPUT

Loose comparison

OUTPUT

Strict comparison

OUTPUT

Type Conversion

Implicit conversion

OUTPUT

Explicit conversion

OUTPUT

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