How do you define a class and its constructor?

A JavaScript Constructor is a function which is used as a constructor that allows you to create an object from a class. A constructor access is one of public, protected and private.

Three ways to define a JavaScript class,

1.      Using as a function

2.      Using as Object Literals

3.      Singleton using as a function

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The Syntax

access NameOfAClass(parameters) {
   initialization code;
}

//Access as public 
public customer(parameters) {
   initialization code;
}

//Access as protected 
protected customer(parameters) {
   initialization code;
}

//Access as private 
private customer(parameters) {
   initialization code;
}

Examples as,

//class declaration inJavaScript
//constructor
var customer = function (id, name, age) { }
customer.prototype = {}

//Instance variables members.
var customer = function (id, name, age) {
    this.id = id;
    this.name = name;
    this.age = age;
}
customer.prototype = {}


//Static variables.
var customer = function (id, name, age) {
    this.id = id;
    this.name = name;
    this.age = age;
}

customer.prototype = {
    staticVar1: 20,
    staticVar2: 'Anil'
}

//Instance functions methods.
var customer = function (id, name, age) {
    this.id = id;
    this.name = name;
    this.age = age;
}

customer.prototype = {
    getId: function () {
        return this.id;
    },

    setId: function (id) {
        this.id = id;
    }
}

//Static functions
var customer = function (Id, name, age) {
    this.id = id;
    this.name = name;
    this.age = age;
}

customer.create = function (Id, name, age) {
    return new customer(Id, name, age);
}
customer.prototype = {}

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What happens when a constructor is called?

1.      It creates a new object.

2.      It sets the constructor property of the object to Vehicle.

3.      It sets up the object to delegate to customer.prototype.

4.       It calls customer() in the context of the new object.

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