Object Prototype

Prototype is something all javascript object have.

The prototype is used for property resolution.

It is used when trying to define a property that is not directly defined on an object.

Example 1:

var person = {
    name: "notset",
    sayHi: function(){
        console.log("hello from" + this.name);
    }
}

//Lets say we wanted to create a manager: 
var manager = {}; 
manager.__proto__ = person; 
manager.sayHi(); -> "hello from notset" //Even though the manager object didn't have a sayHi() function, we can access the sayHi function. 
manager.name = "Bossman"; 
manager.sayHi(); -> "hello from Bossman"

//Which is basically equivalent to: 
var manager2 = {
    name: "Bossman"
    sayHi: person.sayHi
}

//Even object prototype has object. 
//Every object but the object prototype itself has a prototype. 
manager._proto

//We can check if the object has a property: 

manager.hasOwnProptery("sayHi"); -> false
manager.__proto__hasOwnProptery("sayHi"); -> true 

//If we want to say manager.sayHi(), it goes through those setps: 
1. manager.hasOwnProptery("sayHi"); -> false
2. manager.__proto__hasOwnProptery("sayHi"); -> true 
3. manager.__proto_.sayHi.call(manager);

Example 2:

var dummy = "";
dummy.__proto__.sayHi = function() { //Now all string in js has that function
    console.log(this + "hello");
}

var manager = {};
manager.__proto__ = person; 
manager.sayHi(); -> Say hi 
manager.sayHi = undefined; //Please not this does not unset the property 
manager.sayHi(); -> Uncaught TypeError, manager.sayHi is not a value 

manager.hasOwnProperty("sayHi") -> true //Even though its undefined

//How to remove a property, we need to use 'delete': 
delete manager.sayHi
manager.hasOwnProperty("sayHi") -> false