JS question

class_test.js

A = function () {
	
	this.title = null;

	this.config = new A.Config();

	this.test = function () {
		
		console.log( "What scope difference is there between me and A.init() ?" );

	}

};

A.prototype = {
	
	constructor: A,

	init: function ( newTitle ) {
		
		this.title = newTitle;

	}
};

A.Config = function ( width, height ) {

	this.width = width;
	this.height = height;

};

A.Config.prototype = {

	constructor: A.Config,

	init: function ( width, height ) {
		
		this.width = width;
		this.height = height;

		console.log( this.width + " x " + this.height );
		
		console.log( this.title ); // displays: undefined
		console.log( A.title ); // displays: undefined
		console.log( myTest.title ); // displays: "bob"

	}

};

var myTest = new A();

myTest.init( "bob" );

myTest.config.init( 320, 240 );

//	1) How can a prototyped function inside A.Config get access to a var/function from A ?
//	2) What's the difference (scope?) between a prototyped functions:  A.init() vs. A.test() ?

1. You need to pass the instance of A along to A.Config's constructor and reference it in init. It looks like you want A.Config to work like an inner class in Java, but that's not the case.

2. None. 'this' will refer to the instance of A (usually) in both. The form you have with init is better in my opinion. You also don't need to set prototype.constructor, it's implicitly set by 'new' :)

Thank you for taking the time to email me - appreciated. I've since been reading up on JavaScript a lot, especially the way in which the keyword "this" changes scope based on how the object was called. Fascinating stuff! Cheers, Rich

On 15 November 2011 12:57, Bruno Garcia < ***@***.*** > wrote: 1) You need to pass the instance of A along to A.Config's constructor and reference it in init. It looks like you want A.Config to work like an inner class in Java, but that's not the case. 2) None. 'this' will refer to the instance of A (usually) in both. The form you have with init is better in my opinion. You also don't need to set prototype.constructor, it's implicitly set by 'new' :) --- Reply to this email directly or view it on GitHub: https://gist.github.com/1366961

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