Methods are bound to an object as a property : Invoking methods which are 'out-of-context'

method-property.js

//creating a class named Person with a constructor 
var Person = function(firstName){
	this.firstName = firstName;
};

//creating prototpye function to access it, with multiple objects while it is loaded only once in memory
Person.prototype.sayHello = function(){
	console.log("My name is " + this.firstName);
};

//creating two objects from the class Person with inital names
var p1 = new Person("Deepak");
var p2 = new Person("Harman");

//calling the method and assigning it to helloFunction
//sayHello doesnt have a closing brackets, since this variable is created just to test its working
var helloFunction = p1.sayHello;

//printing the respective names
p1.sayHello();	//logs  "My name is Deepak"
p2.sayHello();	//logs  "My name is Harman"

//testing 
console.log(helloFunction === p1.sayHello);		//logs true

///testing again
console.log(helloFunction === Person.prototype.sayHello);		//logs false

//testing again
helloFunction();	//logs error, since there is no object to which it can reference it to.

//testing again
helloFunction.call(p1);		//logs "My name is Deepak" , since it can now reference to the object named p1.