⭐ Objects

Objects are resuable components that contain data and functionality.

In JavaScript, both the data and functionality encapsulated by an object are called properties. If a property has a function value, it’s also known as a method. JavaScript objects can be used to describe physical objects, but they can also be used to describe abstract ideas.

example:

const pencil = {
  length: "7.5 inches",
  shape: "hexagonal",
  diameter: "1/4 inch",
  write: function(){/*do writing*/},
  erase: function(){/*do erasing*/},
  sharpen: function(){/*do sharpening*/},
 }
 ```

Once object is created, you can find out about it and make use of its functions by using dot notation. 

pencil.sharpen();
 const newPencil = {...pencil}; //makes copies of it

## Javascript has four ways to create objects from scratch

- Use object literal notation.
- Use the new keyword.
- Use Object.create().
- Define a class.


### literal notation

```javascript
const person = {eyes: 2, feet: 2, eyeColor: 'brown'};

or

 const person = {};
 person.hair = 'black';
 person.hands = 2;
 person.fullName = {firstName:'Lamont',lastName:'Rudnick'};

Object Constructor

A constructor function is very much like a template or a blueprint for creating objects.

• The constructor function itself is the blueprint. It defines the structure and initial properties that objects created from it will have.
• When you call the constructor with new, you are using that blueprint to create a specific instance (the object). Each instance will have the properties and methods defined in the constructor, but with potentially different values for those properties.

function Cat(name, type){
  this.name = name;
  this.type = type;
 }
 const ourCat = new Cat('Murray', 'domestic short hair');

The keyword this in Listing 7-1 (and elsewhere in this chapter) refers to the context in which a function, such as the constructor function, is running. When you create a new object using the new operator and the Cat() constructor function this refers to the new object

The Cat function expects the name as the first argument and the type as the second.

example:

 class Car {
  constructor(make, model, year) {
    this.make = make;
    this.model = model;
    this.year = year;
  }

  getDescription() {
    return `${this.year} ${this.make} ${this.model}`;
  }
}

const car1 = new Car("Toyota", "Camry", 2023);
const car2 = new Car("Honda", "Civic", 2022);

console.log(car1.make);          // Output: Toyota
console.log(car2.getDescription()); // Output: 2022 Honda Civic

Making objects with class

It's like bringing blueprints to life. A class is a template for objects. Many other languages have the idea of classes, but the notion of a class is relatively new to JavaScript. Class syntax was introduced into JavaScript in 2015 to provide programmers moving to JavaScript with a more familiar way to create objects

class Pet { constructor(name,type){ this.name = name; this.type = type; } } const ourDog = new Pet('Chauncey','AmStaff');