09/06/2011
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The author writes this JavaScript article tutorial for Flash ActionScript developers that have the same interest - like, work with Flash and ActionScript but still want to learn some things new in JavaScript programming language.
Although this JavaScript article tutorial is written for ActionScript programmers, but it is also a very good tutorial for who to learn object-oriented JavaScript programming. This JavaScript article tutorial guides you how to build a full-completed JavaScript object with the getter and setter methods. Please visit for more details.
Other related JavaScript OOP article tutorials:
- JavaScript OOP Tutorial for Dummies
- Pointers in OOP JavaScript
- OOP in JavaScript: Some Basics
- OOP JavaScript: Public and Private Methods
- Basic OOP Concepts in Javascript
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Anyway, there are (ofcourse) some techniques to code like Actionscript in JavaScript. These snippets have helped me to understand object oriented JavaScript. For too long I did not even tried to learn what was possible with JavaScript because I thought it was a very limited language. Maybe some information is outdated; I am still learning, so please share your feedback.
Object oriented javascript
In javascript it is possible to create classes, public and private vars, getters/setters and there are even constructors. A function could be seen as a class. This is a bit strange at first, but if you use it for a while you will understand. Now lets create our own class right now.
Lets port some stuff of this Color Class to javascript. It has private vars and public functions.
Declare classes
Defining classes is as easy as defining functions, because it is almost the same. After creating an function, you could already make some instances of it. The example below creates a Color class with a public variable called value. After that we create 2 instances of the Color class with some other values.
Note: I use the same code conventions as Actionscript: Classes should be UpperCased, functions/vars should be lowerCased and constants should be FULL_CAPS. Oh and since javascript looks like as1.0, I sometimes use an underscore before private vars
{
this.value = value || 0;
alert("Color created with value: " + value)
}
var myRedColor = new Color(0xFF0000); // create instance of Color (a red one)
var myOrangeColor = new Color(0xFFCC00); // create instance of Color (an orange one)
alert( myRedColor.value );
alert( myOrangeColor.value );
Public Private
In actionscript it is very useful to use encapsulation, which is a mechanism for restricting access to other objects. The previous+following example should work in all browsers. The difference between public and private vars/functions in javascript can be declared like this:
{
// public variable
this.value = value || 0xFFFFFF; // set default value to 0xFFFFFF for parameter if it isn�t defined
// private variable
var _name = "test";
// public function
this.getRandomColor = function( )
{
return Math.random() * 0xFFFFFF;
}
// private function
function getNiceColor()
{
return 0xffcc00;
}
}
// create instance of Color
var color = new Color(0xFF0000);
alert( color.value ); // returns red color
alert( color.getRandomColor() ); // returns random color
// not possible :
alert( color.getNiceColor() ); error in console; property does not exist, because function is private.
alert( color._name ); // error in console; property does not exist, because variable is private.
I think with this principles (maybe in combination with namespaces, see below) you can create clean javascript code.
Packages Namespaces
Now before using classes in javascript I had some conflicts with function and variable names because there were unwanted duplicates. I have written a little helper tool to use namespaces. It helps to prevent those conflicts. Now it looks more like Actionscript 3, only there is no such thing like �imports�. This snippet works in all browsers.
function Namespace(namespace)
{
var parts = namespace.split(".");
var root = window;
for(var i = 0; i < parts.length; i++)
{
if(typeof root[parts[i]] == "undefined")
{
root[parts[i]] = {};
}
root = root[parts[i]];
}
}
// creating my own namespace here
Namespace("nl.stroep.utils");
nl.stroep.utils.Color = function(value) // create class inside package
{
this.value = value || 0xFFFFFF;
}
var myRedColor = new nl.stroep.utils.Color(0xff0000);
alert(myRedColor.value);
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09/06/2011
The author writes this JavaScript article tutorial for ...Helpful JavaScript Tutorial for ActionScript 3 Developers - Helpful JavaScript Tutorial for ActionScript 3 Developers - Language: English
