JavaScript-Folder/Functions.html at main · researcher-program/JavaScript-Folder · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>  Function | JavaScript | Al- Arafat </title>
</head>
<body>
    <H1> Assalamualaikum Or-Rohmatullah </H1>
    <H2> Al -  Arafat </H2>
</body>
<script src="Functions.js"></script>
<script src="test-12.js"></script>
<script>
    // Type-1:


/*
                            FUNCTION :
*/

/*
        // This is not a Function Definition or Syntax/Structure:

console.log("A");
console.log("R");
console.log("A");
console.log("F");
console.log("A");
console.log("T");
console.log("H");
console.log("E");
*/

/*
                        Basic Of Functions:
            //Function's Definitions:
            Type :- 01
function sayMyName()
{
 console.log("A");
 console.log("R");
 console.log("A");
 console.log("F");
 console.log("A");
 console.log("T");
 console.log("H");
 console.log("E");
}
// sayMyName ==> //This is function's "reference",

sayMyName() // when "()" this function sign means "execute".
*/
// Now,Real Function's Basics Structure :
                // Type :- 02
function addTwoNum(num1,num2) {
    // console.log(num1+num2);
}
// addTwoNum() //Output: NaN
addTwoNum(3,4) // OutPut: 7
// addTwoNum(3,"4") // What if? ==>34,because "4" is a string that's why js think 3 is also string,that how become =>34


// addTwoNum(3,"a") // What if? ==>3a,because "a" is a string that's why js think 3 is also string,that how become =>3a


// addTwoNum(3,null) // What if? ==>3
/*
Difference about "Parameters" and "Arguments" :

function addTwoNum2(num1,num2) ==> (num1,num2)--> Parameters
addTwoNum2(3,4) ==>(3,4)--> Arguments
*/

/*
                            //  Type :- 03
function addTwoNum2(num1,num2) {
    console.log(num1+num2);
}
addTwoNum2(3,4)

function addTwoNum3(num1,num2) {
    console.log(num1+num2);
}
addTwoNum3(3,"4","a")

function addTwoNum4(num1,num2) {
    console.log(num1+num2);
}
addTwoNum4(3,null)

function addTwoNum5(num1,num2) {
    console.log(num1+num2);
}
*/
        //Store In Variables:
                   //  Type :- 04
const result1 = addTwoNum5(3,45)
console.log("Result: ",result1); //undefined

                        //  Type :- 05
function addTwoNum6(num1,num2) {
    // Not print anythings because not execute "console.log"
    // but,if i do "console.log" then what?
    let result2 = num1+num2
    console.log("Arafat");
    return result2
    // console.log("Arafat");

    // console.log("Arafat"); //The answar is :not print/execute this "console.log", because,"return" পরে কিছু লিখলে তা কখনোই "print" হয় না,"return"এর উপরে  "console.log" থাকলে "print" হয় না।

}
const result2 = addTwoNum5(3,5)
console.log("Result: ",result2);
/*
// Extra : copy on "result2"
                        //  Type :- 06
function addTwoNum6(num1,num2) {

    let result3 = num1+num2
    console.log("Arafat");
    return result3
    // console.log("Arafat");
}
const result3 = addTwoNum5(3,5)
console.log("Result: ",result3);
*/

                //  Type :- 07
function addTwoNum7(num1,num2) {
    let result4 = num1+num2
    return result4
    // console.log("arafat");
}
                        // Type :- 08
const result5 = addTwoNum7(3,45)
console.log("Result: ",result5);

                //  Type :- 09
function addTwoNum8(num1,num2) {
    let result6 = num1+num2
    console.log("arafat");
    return result6


}
            //  Type :- 10
const result7 = addTwoNum8(3,45)
console.log("Result: ",result7);

                //  Type :- 11
function addTwoNum9(num1,num2) {
    // let result8 = num1+num2
    // console.log("arafat");
    // return result8
    return num1+num2
}
const result8 = addTwoNum9(3,45)
console.log("Result: ",result8);
/*
                //  Type :- 12
function loginUserMessage(username) {
    return ` ${username} Just Logged In.`

}

// loginUserMessage()
// loginUserMessage("Arafat")
// console.log(loginUserMessage("")); //no change
// console.log(loginUserMessage()); //undefined
// console.log(loginUserMessage("Arafat"));
*/

/*
                //  Type :- 13
function loginUserMessage1(username1) {
    if (username1===undefined) {
        console.log("Please Enter Your UserName");
        return
    return ` ${username1} Just Logged In.`
    }
    return ` ${username1} Just Logged In.`

}
// loginUserMessage1()
// loginUserMessage1("Arafat")
// console.log(loginUserMessage1("Arafat"));
// console.log(loginUserMessage1(""));
console.log(loginUserMessage1());
*/
/*
                //  Type :- 14 : Same Output:Type :-13
function loginUserMessage1(username1) {
    if (!username1) {
        console.log("Please Enter Your UserName");
        return

    }
    return ` ${username1} Just Logged In.`

}
// loginUserMessage1()
// loginUserMessage1("Arafat")
// console.log(loginUserMessage1("Arafat"));
// console.log(loginUserMessage1(""));
console.log(loginUserMessage1());

//  ("") ==> Empty String /(undefined)==> False Value.
*/
                         //  Type :- 15
function loginUserMessage2(username2="Samy") {
     if (!username2) {
        console.log("Please Enter Your UserName");
        return
     }
    return ` ${username2} Just Logged In.`

}
// loginUserMessage()
// loginUserMessage("Arafat")
// console.log(loginUserMessage2());

/*
                            //  Type :- 16
function loginUserMessage2(username2="Samy") {
     if (!username2) {
        console.log("Please Enter Your UserName");
        return
     }
    return ` ${username2} Just Logged In.`

}
// loginUserMessage()
// loginUserMessage("Arafat")
// console.log(loginUserMessage2());
console.log(loginUserMessage2("Arafat")); // override "Samy"

*/
                    //  Type :- 17

function calculateCartPrice(num1) {
    return num1
}
console.log(calculateCartPrice(2));
/*
                Type :- 18
If ,
console.log(calculateCartPrice(200,400,53545,453,2425));
Then What ?
The Answar Is:
restOperator{...} / spreadOperator.
*/
function calculateCartPrice(...num2) {
    return num2
}
console.log(calculateCartPrice(200,400,53545,453,2425));

            //  Type :- 19
function calculateCartPrice(val1,val2,...num3) {
    return num3
}
console.log(calculateCartPrice(200,400,53545,453,2425));
/*
            Type :- 20
                         //Objects:

const user = {
    userName: "Arafat",
    price:164
}
*/
function handleObject(anyobject) {
console.log(`UserName is ${anyoject.userName} and price is ${anyoject.price}`);
}
handleObject(user)


/*
            Type :- 21

const user = {
    userName: "Arafat",
    prices:164 //if I replaces as "price" in "prices".....",handleObject(user) " // undefined
}
*/
function handleObject(anyobject) {
console.log(`UserName is ${anyoject.userName} and price is ${anyoject.price}`);
}
handleObject(user) // undefined

        //  Type :- 22 :Same OutPut:Type:-21
handleObject({
    userName:"sam",
    price:356
})
            //  Type :- 23
                        //   Arrays:
const myNewArray = [200,400,100,544]
function returnSecondValue(getArray) {
    return getArray[1]
}
console.log(returnSecondValue(myNewArray));
// Or,
console.log(returnSecondValue([
    200,400,100,544 //same output
])); // Override "myNewArray"

</script>
<script>
    // Type-2:


/*
console.log("A");
console.log("R");
console.log("A");
console.log("F");
console.log("A");
console.log("T");
console.log("H");
console.log("E");
*/
/*
function sayMyName()
{
 console.log("A");
 console.log("R");
 console.log("A");
 console.log("F");
 console.log("A");
 console.log("T");
 console.log("H");
 console.log("E");
}
sayMyName
sayMyName()
*/
/*
function addTwoNum(num1,num2)//parameters
 {
    console.log(num1+num2);
}
// addTwoNum()
// addTwoNum(3,4)
// addTwoNum(3,"4")
// addTwoNum("3",4)
// addTwoNum(3,"a")
// addTwoNum(3,null)
// addTwoNum(3,4,8) // Only add first two numbers/arguments/values.
const result = addTwoNum(4,5)
console.log("Result: ",result);//undefined
*/
/*
function addTwoNum(num1,num2)
 {
    let result = num1 + num2;
    console.log("Arafat");
    return result;
    console.log("Arafat"); //This line will never execute because it's after the return statement.
}
const result = addTwoNum(4,5)
console.log("Result: ",result);
*/
function addTwoNum(num1,num2)
 {

    return num1 + num2 ;

}
const result = addTwoNum(4,5)
// console.log("Result: ",result);


function loginUserMessage(username) {
    return ` ${username} Just Logged In.`

}
/* No need to call function again and again:

// loginUserMessage()
// loginUserMessage("Arafat")
// console.log(loginUserMessage("")); //no change
// console.log(loginUserMessage()); //undefined
*/
// console.log(loginUserMessage("Arafat"));


function loggedInUserMessage(userName) {
    if (userName===undefined) {
        console.log("Please Enter Your UserName");
        return
    // return ` ${userName} Just Logged In.`
    }
    return ` ${userName} Just Logged In.`

}
/*
// loggedInUserMessage()
// loggedInUserMessage("Arafat")
// console.log(loggedInUserMessage(""));
// console.log(loggedInUserMessage());
*/
// console.log(loggedInUserMessage("Arafat"));

function loginUserMessage1(username1) {
    if (!username1) {
        console.log("Please Enter Your UserName");
        return

    }
    return ` ${username1} Just Logged In.`

}
/*
// loginUserMessage1()
// loginUserMessage1("Arafat")
// console.log(loginUserMessage1(""));
// console.log(loginUserMessage1());
//  ("") ==> Empty String /(undefined)==> False Value.
*/
// console.log(loginUserMessage1("Arafat"));


function loginUserMessage2(username2="Samy") {
     if (!username2) {
        console.log("Please Enter Your UserName");
        return
     }
    return ` ${username2} Just Logged In.`

}
/*
// loginUserMessage2()
// loginUserMessage2("Arafat")
*/
// console.log(loginUserMessage2());
// console.log(loginUserMessage2("aRAFAT")); // override "Samy"


function loginUserMessage2(username2="Samy") {
     if (!username2) {
        console.log("Please Enter Your UserName");
        return
     }
    return ` ${username2} Just Logged In.`

}
// loginUserMessage2()
// loginUserMessage2("Arafat")
// console.log(loginUserMessage2());
// console.log(loginUserMessage2("Arafat")); // override "Samy"


function calculateCartPrice(num1) {
    return num1
}
// console.log(calculateCartPrice(2));

// console.log(calculateCartPrice(200,400,600,800)); //Prblem: only first argument will consider.
/*
If ,
console.log(calculateCartPrice(200,400,53545,453,2425));
Then What ?
The Answar Is:
restOperator{...} / spreadOperator.
*/

function calculateCartPrice(...num2) {
    return num2
}
// console.log(calculateCartPrice(200,400,53545,453,2425));

function calculateCartPrice(val1,val2,...num3) {
    return num3
}
// console.log(calculateCartPrice(200,400,53545,453,2425));
// console.log(val1); // Occurs Error: val1 is not defined
// console.log(val2); // Occurs Error: val2 is not defined


      //Objects in Functions:
const user = {
    userName: "Arafat",
    price:164
}
function handleObject(anyobject) {
// console.log(`UserName is ${anyobject.userName} and price is ${anyobject.price}`);
}
// handleObject(user)
/*
    // Intentionally Mistakes/Errors for Learning Purpose:
    const user = {
    userName: "Arafat",
    prices:164
}
function handleObject(anyobject) {
console.log(`UserName is ${anyobject.userName} and price is ${anyobject.price}`);
}
handleObject(user)

//That's Why Need here " TypeScript " for avoiding this type of mistakes/errors.
*/


function handleObject(anyobject) {
console.log(`UserName is ${anyobject.userName} and price is ${anyobject.price}`);
}/*
handleObject({
    userName:"sam",
    price:356
})
*/
        //   Arrays:
const myNewArray = [200,400,100,544]
function returnSecondValue(getArray) {
    return getArray
    // return getArray[1]
    // return getArray[] // Occurs Error: Unexpected token ']' // SyntaxError: Unexpected token ']'
}
// console.log(returnSecondValue(myNewArray));

// Or,

console.log(returnSecondValue([
    200,400,100,544,520 //same output
])); // Override "myNewArray"

</script>
</html>