World-Of-JAVASCRIPT

This README is going to be best for learning javascript.

Why javascript ?

javaScript improves the user experience of the web page by converting it from a static page into a interactive one.

OR

Javascript adds behaviour to a web page

console.log()

To print hellow world using console

    console.log('Hello World');

SECTION 1: VALUES AND VARIABLES

Lets take a example:

    var MyName = 'Sunny Raj'

From the above exapmle:
var is a statement which declares a variable in javaScript.
MyName is a variavle name.
'Sunny Raj' is the value.
Variables are containers for storing information. Creating a variable in JavaScript is called "declaring" a variable: var MyName;

RULES FRO GIVING VARIABLE NAME

The first character must be a letter or an underscore_ or Dollar$.

    var MyName = 'Sunny Raj';
    var $MyName = 'Sunny Raj';
    var _MyName = 'Sunny Raj';

You cant use a number as the first character var 1MyName = 'Sunny Raj';
The rest variable name can include any letters, any number, or the underscore.

    var _1My__Name = 'Sunny Raj';

Cant use any other character, including spaces

    var _MyName% = 'Sunny Raj';
    var  My Name= 'Sunny Raj';  ---> WRONG VARIABLE NAME

Variable name are case sensitive: myname AND MyName are NOT same.
No Limit to the length of variable name ( That dont mean you use a long variable name, it should be meaningfull).
You can't use Javascript reserved words as a variable name.

SECTION 2: DATA TYPE (PRIMITIVE)

Undefined: var IamStandby;
Boolean: var IamRaj = true;
Number: var MyAge = 20;
String: var MyName = 'Sunny Raj;'
Bigint: ?
Symbol:

typeof()

To find the datatype of the variable.

    console.log(typeof(MyName));

    OUTPUT: string

Q1. What is difference between null and undefined ?

var IamUseless = null; : variable Defined and given value null.
var IamStandBy; : No value Given

Q2. What is NaN ?

NaN stands for Not-A-Number.
If We subtract two string we get NaN:

     console.log("Sunny" - "Raj");

     OUTPUT: NaN

NaN is a property of the global object.
In other words, it is a variable in global scope.

isNaN()

This return true if the

var MyPhoneNumber = 987654321;
var MyName = "Sunny Raj";
console.log(isNaN(MyPhoneNumber));   OUTPUT:false
console.log(isNaN(MyName));          OUTPUT:true

SECTION 3: EXPRESSION AND OPERATOR

    Expression -> (Operand + Operator)
    Expression -> (4 + 67)

Where 4,67 are operand and (+) is operator.
There are following type of Operators:

    1. Assignment Operator
    2. Comparision Operator
    3. Logical Operator
    4. String Operator
    5. Conditional (ternary) Operator
    6. Increament & Decrement Operator

ASSIGNMENT OPERATOR

An assignment operator assigns a value to its left operand. Based on the value of its right operand.
The simple assignment operator is equal (=).

    var x =5;
    var y =5;

COMPARISON OPERATOR

Equal (==)

    var a = 30;
    var b = 10;
    console.log(a==b); // false

Not equal (!=)

    var a = 30;
    var b = 10;
    console.log(a!=b); // true

Graeter than (>)

    var a = 30;
    var b = 10;
    console.log(a>b);  // true

Graeater than and equal to (>=)

    var a = 30;
    var b = 10;
    console.log(a>=b); // true

less than (<)

    var a = 30;
    var b = 10;
    console.log(a<b);  // false

Less tahn equal to (<=)

    var a = 30;
    var b = 10;
    console.log(a<=b); // false

LOGICAL OPERATOR

Logical AND (&&)

It is also known as Logical Conjuction.
Is true if and only if all of its operands are true

        var a = 30;
        var b = -20;
        console.log(a > b && b > -56 && b < 0);

Logical OR (||)

It is also known as Logical Disjunction.
Is true if and only if one or more of its operands are true

        var a = 30;
        var b = -20;
        console.log(a > b || b > 0 || a < 0);

Logical NOT (!)

It is also known as Logical complement, Negation.
Takes truth to falsity and vice versa.

        var a = 30;
        var b = -20;
        console.log(!(a>0 || b<0));
        console.log(!true);
        console.log(!false);

STRING OPERATOR & CONCATINATION

CONDITIONAL (TERNARY) OPERATOR `( ) ? :`

        var age = 17;
        console.log((age >18) ? "VOTE" : " Cant VOTE");

STRING CONCATINATION OPERATOR

The concatination operator (+) concatenates two string values together. returning another string that is union of the two optand strings.

        console.log('Hello World');          // Hello World
        console.log('Hello'+'World');        // HelloWorld
        console.log('Hello '+'World');       // Hello World   ---> Giving space inside the quotes
        console.log('Hello'      + 'World'); // HelloWorld    ---> Giving space outside the quotes 

        var MyName = 'Sunny';
        console.log(MyName + 'Raj');        // SunnyRaj

INCREMENT & DECREMENT OPERATOR

        var num = 5;
        var newnum = num++ + 5;
        console.log(num);
        console.log(newnum);

EXPONENTIAL OPERATOR

The Operator (**) is To the power operator.
Below are some example:

(5**6) ---> 5*5*5*5*5*5

EXPLAINATION: Now 5**6 is spell as 5 to the power 6 (i.e 55555*5).

console.log(2**3);      OUTPUT:8
console.log(3**3);      OUTPUT:27

EXPLAINATION: Now 2**3(i.e 222) will give output as 8 & For 3**3(i.e 333) the output will be 27. Q1. What will be the output of (2** -1)?

SECTION 4: CONTROL STATEMENT & LOOPS

IF...ELSE

            var age = 18;
            if(age >= 18){
                console.log("Vote");
            } else {
                console.log("Cant Vote");
            }

NESTED IF...ELSE

var area = "circle"
var PI = 3.142, l=5, b=4, r=3;
if(area = "circle"){
    console.log("the area of the circle is:" + PI*r**2);
} else if(area = "triangle"){
    console.log("the area of the triangle is:" + (l+b)/2);
} else if(area = "rectangle"){  
     console.log("the area of the rectangle is:" + (l*b));
} else{  
    console.log("Please enter a valid shape");
}

SWITCH STATEMENT

Switch(area)
{
case 'circle':
    console.log("the area of the circle is:" + PI*r**2);
    break;
case 'triangle':
    console.log("the area of the triangle is:" + (l+b)/2);
    break;
case 'rectangle':
    console.log("the area of the rectangle is:" + (l*b));
    break;
default:
    console.log("Please enter a valid shape");
}

WHILE LOOP

var num=0;
while(num<=10)
{
    console.log(num);
    num++;
}

DO-WHILE LOOP

var num=0;
do{
    console.log(num);
    num++;
}while(num<=10);

FOR LOOP

for(var num = 0; num<=10; num++)
{
    console.log(num);
}

SECTION 5: FUNCTION

function <NAME> ()
{
// Statement
}
---------EXAMPLE---------
function Sum(){
var a=10, b=20;
var total = a+b;
console.log(totle);
}
Sum(); // Function Calling

Q. Why do we use Function?

Reusability of code
Define code once and use many times.

Q. What is difference between Function Parameter and Function Argument ?

function Sum(a,b){  ---> a,b are Parameters 
var total = a+b;
console.log(totle);
}
Sum(20,30);         ---> 20,30 are Arguments

FUNCTION EXPRESSION & RETURN KEYWORD

function Sum(a,b){ 
return total = a+b;
}
ver funExp = Sum(15,20);
console.log(funExp);

sunnyraj5555/World-Of-JAVASCRIPT

World-Of-JAVASCRIPT

Why javascript ?

console.log()

SECTION 1: VALUES AND VARIABLES

RULES FRO GIVING VARIABLE NAME

SECTION 2: DATA TYPE (PRIMITIVE)

typeof()

isNaN()

SECTION 3: EXPRESSION AND OPERATOR

ASSIGNMENT OPERATOR

COMPARISON OPERATOR

Equal (==)

Not equal (!=)

Graeter than (>)

Graeater than and equal to (>=)

less than (<)

Less tahn equal to (<=)

LOGICAL OPERATOR

Logical AND (&&)

Logical OR (||)

Logical NOT (!)

STRING OPERATOR & CONCATINATION

CONDITIONAL (TERNARY) OPERATOR ( ) ? :

STRING CONCATINATION OPERATOR

INCREMENT & DECREMENT OPERATOR

EXPONENTIAL OPERATOR

SECTION 4: CONTROL STATEMENT & LOOPS

IF...ELSE

NESTED IF...ELSE

SWITCH STATEMENT

WHILE LOOP

DO-WHILE LOOP

FOR LOOP

SECTION 5: FUNCTION

FUNCTION EXPRESSION & RETURN KEYWORD

CONDITIONAL (TERNARY) OPERATOR `( ) ? :`