# Constructor and Prototype

• Core Concepts
• Function, Prototype, and Instance Relationships
• Prototype Chain
  • Comparison of Constructor and Prototype

# Core Concepts

In JavaScript, every object has a prototype. The prototype is also an object. When you create an object, JavaScript automatically assigns the prototype of the object to the prototype of the constructor function that created the object.

1. Constructor: This is the function that is used to construct or create (initialize) the object. You can access it via object.constructor.
   
   
2. Prototype: This is the object from which the object inherits properties and methods. You can access it via Object.getPrototypeOf(object).
   
   
3. Constructor Chain: In class-based inheritance, constructors form a lineage reflecting the hierarchy of classes for inheritance.
   
   
4. Prototype Chain: JavaScript's inheritance mechanism. When accessing a property or method, JavaScript traverses the prototype chain until it finds the property or reaches null.

FYI, I need to preface the following diagram with "I think"

# Function, Prototype, and Instance Relationships

    graph LR
    myFunc[myFunc Function] -->|has| FunctionProperties[Function Properties]
    myFunc -->|has| FunctionMethods[Function Methods]
    myFunc -->|has| FunctionPrototype[myFunc.prototype]
    FunctionPrototype -->|has| Constructor[constructor: myFunc]
    FunctionPrototype -->|has| OtherProperties[Other properties and methods]
    obj[obj Instance] -->|has| InstanceProto[obj.__proto__]
    InstanceProto -->|points to| FunctionPrototype

# Prototype Chain

    graph LR
        Constructor -->|has| Prototype[Prototype]
        Prototype -->|has| BasePrototype[Base Prototype]
        Constructor -->|creates| Instance
        Instance -->|links| Prototype
        BasePrototype -->|__proto__ points to| Null[null]

# Comparison of Constructor and Prototype

The following example demonstrates the difference between a constructor and a prototype.

class Person {
    constructor(name) {
        this.name = name;
    }
}

const user = new Person('Joanne');
console.log(user.name);

function Animal(name){
    this.name = name;
}

let pet = new Animal('Fluffy');
console.log(pet.name);

In the above example, both create objects with a name property. The difference is that Person is a class that uses a constructor method to initialize its name property. Animal is a function that uses the this keyword to assign its name property.