Function


Function =


Define code once, and use it many time

To perform some code, call the function name

console.log("Happy new year")
console.log("Happy new year bro!")
console.log("Happy new year Mauro!")
console.log("Happy new Elena!")
console.log("Happy birthday dear ___")

We can image this as 5 different function
happy() //Need to invoke the function

function happy(){
console.log("Happy new year")
console.log("Happy new year bro!")
console.log("Happy new year Mauro!")
console.log("Happy new yearElena!")
console.log("Happy birthday dear ___")
}
let userName = "Bro"
let age = 22

happy() //Need to invoke the function

function happy(){
console.log("Happy new year")
console.log("Happy new year bro!")
console.log("Happy new year Mauro!")
console.log("Happy new yearElena!")
console.log("Happy birthday dear", userName, "Now you are", age, "years old")
}

result:

Happy new year
function.js:10 Happy new year bro!
function.js:11 Happy new year Mauro!
function.js:12 Happy new year Elena!
function.js:13 Happy birthday dear Bro Now you are 22 years old

//possiamo usare le variabili in differenti funzioni
//importante è inserirle tra le parentesi della funzioone
//devono essere uguali



startProgram()

function startProgram(){
let userName = "Bro"
let age = 22

happy(userName, age)
}

function happy(userName, age){
console.log("Happy new year")
console.log("Happy new year bro!")
console.log("Happy new year Mauro!")
console.log("Happy new year Elena!")
console.log("Happy birthday dear", userName, "Now you are", age, "years old")
}

result: the same as above

Same result in a different way
Arguments


startProgram()

function startProgram(){
let userName = "Bro"
let age = 22

happy(userName, age) // Argument
}

function happy(a, b){ // A and B is an argument means userName and age
console.log("Happy new year")
console.log("Happy new year bro!")
console.log("Happy new year Mauro!")
console.log("Happy new year Elena!")
console.log("Happy birthday dear", a, "Now you are", b, "years old")
}

result: the same as above