appending to objects

[mjpearson]

I'm relatively new to JS. I read somewhere that I can do the following:

function stuff ( item ) {
this.valuable = item;
}

my_junk = new stuff( "teddy bear" );

function containers( container_item ) {
this.container = container_item;
}

my_container = new containers( "house", my_junk );

document.write( my_container.my_junk.valuable );

**********************
But I can't get it to work, however, I've seen it done this way [and I can get this to work]:
**********************
my_container = new containers( "house" );
my_container.my_junk = my_junk;

document.write( my_container.my_junk.valuable );

**********************
Did mis-read something? I'd prefer to use the first syntax to make life easier. What am I doing wrong?


mike

 

[BillyRayPreachersSon]

The first syntax you use has a flaw in it - you're passing two arguments to the constructor of "containers", and yet you're only receiving 1 argument into the constructor. Perhaps this is why you're not expecting the results you want?

You're also writing out a property of your "container" called "my_junk", which does not exist (you've never defined a property called "my_junk" in the context of "my_container".

Try something like this:

function stuff(item) {
	this.valuable = item;
}

my_junk = new stuff('teddy bear');

function containers(container_name, container_item) {
	this.name = container_name;
	this.item = container_item;
}

my_container = new containers('house', my_junk);

document.write('Inside the container named: ' + my_container.name + ' there is an item: ' + my_container.item.valuable);

Dan



Coedit Limited - Delivering standards compliant, accessible web solutions

[tt]Dan's Page [blue]@[/blue] Code Couch

http://www.codecouch.com/dan/

[/tt]

 

[BillyRayPreachersSon]

Also, read up on "prototype" (not to be confused with the Prototype JS framework) and OO JS techniques:

http://www.crockford.com/javascript/inheritance.html

http://mckoss.com/jscript/object.htm

http://www.webreference.com/programming/javascript/gr/column18/index.html

http://www.webreference.com/js/column79/5.html

http://www.sitepoint.com/article/oriented-programming-1

Dan



Coedit Limited - Delivering standards compliant, accessible web solutions

[tt]Dan's Page [blue]@[/blue] Code Couch

http://www.codecouch.com/dan/

[/tt]

 

[BillyRayPreachersSon]

mike,

Did that work for you?

Dan



Coedit Limited - Delivering standards compliant, accessible web solutions

[tt]Dan's Page [blue]@[/blue] Code Couch

http://www.codecouch.com/dan/

[/tt]

 

[mjpearson]

Thanks,

I've been busy but meaning to write back. I went to some of the references that you provided and several were well over my head but I hope to revisit them soon and really sit down and study them in depth.

Yes, I came to the same conclusion about passing arguements thus my original question. I suspect the book I was referencing was wrong or incomplete.

I used your technique and it worked.

Thanks again,


mike