Playing with classes and objects in Javascript

So, let’s play a little bit with classes and objects in Javascript. If you come from the class based languages like Java and C++, the way we handle classes in javascript looks a little bit strange. First, javascript is not class based, so, it doesn’t have the entity class. A class in javascript is a function. So we can see a simple class in the example below:

MyClass = function(){
};
var instance = new MyClass();

So, to create a new class in javascript we only need to define a new function.

As we know, class has attributes. We could add attributes to our class this way:

MyClass = function(){
  this.attribute = 'Hello';
}
var instance = new MyClass();
alert(instance.attribute);

So, it is not too different as we have on other languages.

We also could pass parameters in the constructor , so we can initialize the class attributes.

MyClass = function(attrValue){
  this.attribute = attrValue;
}
var instance = new MyClass("Hello Class");
alert(instance.attribute);

We can do the same for functions on our class:

MyClass = function(attrValue){
  this.attribute = attrValue;
  this.classFunction = function (){alert('Class function')};
}
var instance = new MyClass("Hello Class");
alert(instance.attribute);
instance.classFunction();

Let’s us create a new class called Person. It should have two attributes: name and age, and a function toString that should display its attributes values. The code will be like this:

var Person = function(){
    this.name = '';
    this.age = '';
    this.toString = function(){
        return "Name:"+ this.name + " - Age:" + this.age;
    };
}
var onePerson = new Person();
onePerson.name = 'Junior';
onePerson.age = '23';

alert(onePerson.toString());

This was a simple introduction for classes on Javascript.

See you in the next post.

Xico Junior

Playing with classes and objects in Javascript