Emmanuel Orozco

Object Oriented Programing for Objects

Hello, object.

Imagine we’re going to tell a computer about you.

1. What’s your name?
2. How old are you?
3. What is your favorite ice cream?

In a programing world with out objects, you only need to create variables and assign values.

let name = "Emmanuel";
let age = 24;
let favoriteIceCream = "vanilla";

But, there is a problem when it comes to scalability. What if we want to create many people? We would need to create more variables

let name1 = "Emmanuel";
let age1 = 24;
let favoriteIceCream1 = "vanilla";

let name2 = "Peter";
let age2 = 25;
let favoriteIceCream2 = "strawberry";

Which, in scalability terms, is a disaster. (An app can have millions of users)

What if there was a better way to structure our code?

What is Object-Oriented Programming?

To answer that, we need to ask a more concrete question.

What is an object?

Concretely: An object is a collection of properties and values.

You are an object, the person next to you is an object. We’re all objects!

You, as an object (an object called ‘person’), have different properties, such as a name, an age, and a favoriteIceCream.

These same properties can apply to another person (a different person who also has a name, age, and favoriteIceCream).

That “mold” of properties (the same properties that can apply to different people) is called a “class,” and in Javascript, it is defined like this:

function Person(name, age, favoriteIceCream) {}

As you can see, defining a class is the same as defining a function since it has input parameters. (Remember that for naming classes, we use the CamelCase format).

As mentioned earlier, people also have characteristics we share with other people (name, age, favoriteIceCream), these characteristics are called properties, and in Javascript, we define them like this:

function Person(name, age, favoriteIceCream) {
  this.name = name;
  this.age = age;
  this.favoriteIceCream = favoriteIceCream;
}

By using the reserved word this, we refer to the current object, so the input parameters will be assigned to that Person object.

The power of using objects is that we can create new people with a single line of code using the reserved word: new.

var Emmanuel = new Person("Emmanuel", 24, "vanilla");

And not just that, you can create people without creating so many isolated variables. (I didn’t need 9 variables to store 3 different properties of 3 people, just 3 variables for 3 people).

var Emmanuel = new Person("Emmanuel", 24, "vanilla");
var Peter = new Person("Peter", 27, "lemon");
var Andrea = new Person("Andrea", 18, "peach");

Just like we share properties, we also share actions; these actions are called: methods. For example, all people in the world can greet each other.

function Person(name, age, favoriteIceCream) {
  this.name = name;
  this.age = age;
  this.favoriteIceCream = favoriteIceCream;
  this.canVote = function () {
    return age >= 18;
  };
}

As we can see, now we’ve added the canVote property, but this time it’s not a numeric variable or a string; it’s a function, which will execute every time we call that method. We can do it like this:

var Emmanuel = new Person("Emmanuel", 25, "vanilla");
Emmanuel.canVote();
// true
var Andres = new Person("Andres", 17, "Strawberry");
Andres.canVote();
// false

We’re using two variables: Emmanuel (var Emmanuel) and Andrés (var Andres), to store two different people who share the same class (they share the Person class). That “variable” is what’s called an object, which is an instance of a class.

If we wanted to access a property of a class, we could do it like this:

var Emmanuel = new Person("Emmanuel", 25, "vanilla");
Emmanuel.age;
// 25

Notice the difference between calling a property and calling a method:

var Emmanuel = new Person("Emmanuel", 25, "vanilla");
Emmanuel.age;
Emmanuel.canVote();

To call the method we use parentheses, but for the property, we don’t.

Remember that a method stores functions, and a property stores numbers, strings, booleans, etc. (but not functions).

In conclusion, to avoid creating a million variables in your code. Create Objects instead.

Happy coding, and may your objects always be as delightful as your favorite scoop of ice cream!