basic_oops.js

/**
 *  const name = 'Rex';
    const age = 2;
    const color = "brown";

    function description() {
        console.log(
            `This is ${name}, he is ${age} years old and his color is ${color}`
        )
    }


    description();
    // This is an example of functional programming. 
    // The function description is a pure function. 
    // It does not depend on any external variables. 
    // It only uses the variables that are passed
    // to it as arguments. This is a good practice. 
    // It makes the code more readable and easier to maintain. 
    // It also makes the code more testable.
 */

function Dog() {
    
    const name = 'Rex';
    const age = 2;
    const color = "brown";

    function description() {
        console.log(
            `This is ${name}, he is ${age} years old and his color is ${color}`
        )
    }

    function makeSound() {
        if (age < 2) {
            console.log("barf .. barf");
        } else {
            console.log("woof .. woof");
        }
    }

    return {
        description: description,
        makeSound: makeSound
    };
} // returns an object

const myDog = Dog(); // call to Dog returns an object; hence myPet is an object
myDog.description();
myDog.makeSound();