01-functions.js

function logger() {
    console.log('My name is Debu');
}

// Calling / running / invoking function

logger();
logger();
logger();

function fruitProcessor(apples, oranges) {
    const juice = `Juice with ${apples} apples and ${oranges} oranges`;
    return juice;
}
const appleJuice = fruitProcessor(5, 0);
console.log(appleJuice);

const appleOrangeJuice = fruitProcessor(2, 4);
console.log(appleOrangeJuice);
const num = Number('23');

// FUNCTION DECLARATION VS. EXPRESSIONS :

// Function declaration -
function calcAge1(birthYear) {
    return 2037 - birthYear;
}
const age1 = calcAge1(1991);

// Function expression
const calcAge2 = function (birthYear) {
    return 2037 - birthYear;
}
const age2 = calcAge2(1991);
console.log(age1, age2);

// ARROW FUNCTIONS :
/*
const calcAge3 = birthYear => 2037 - birthYear;
const age3 = calcAge3 (1991);
console.log (age3);

const yearsUntilRetirement = (birthYear, firstName) => {
   const age = 2037 - birthYear;
   const retirement = 65 -age;
   //return retirement ;
   return `${firstName} retires in ${retirement} years`;
}
console.log (yearsUntilRetirement(1991, 'Jonas'));
console.log (yearsUntilRetirement(1980, 'Bob'));
*/

// FUNCTION CALLING OTHER FUNCTIONS :

function cutFruitPieces(fruit) {
    return fruit * 4;
}
function fruitProcessor(apples, oranges) {
    const applePieces = cutFruitPieces(apples);
    const orangePieces = cutFruitPieces(oranges);
    const juice = `Juice with ${applePieces} pieces of apple and ${orangePieces} pieces of orange`;
    return juice;
}
console.log(fruitProcessor(2, 3));

// REVIEWING FUNCTION :

const calcAge = function (birthYear) {
    return 2037 - birthYear;
}
const yearsUntilRetirement = function (birthYear, firstName) {
    const age = calcAge(birthYear);
    const retirement = 65 - age;
    if (retirement > 0) {
        console.log(`${firstName} retires in ${retirement} years`);
        return retirement;
    } else {
        console.log(`${firstName} has already retired`);
        return -1;
    }
}
console.log(yearsUntilRetirement(1991, 'Jonas'));
console.log(yearsUntilRetirement(1950, 'Maik'));