Array talk

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jens1701

Hi,

playing arround with arrays i discovered two different kinds of arrays.

Have look on this code:

var temp = gallery_list.getElementsByTagName('dd');
var tumb = new Array();
for(var i = 0; i < temp.length; i++){
	if(temp[i].className == 'view_button')
	   tumb.push(temp[i]);
}
view_button_list = tumb;

The temp array is as you can see provided by the 'getElementsByTagName'-Method.
The tump array is put together by a custom loop.

If i look with firebug at the arrays, i get different readings(see attached image01.jpg). While 'temp' got its length property and its unique methods.
'tumb' does not. How come? Whats the difference?

And how do i make a custom element array like one that is created by getElementsByTagName.

Hope you can help out.

Greets

Jens

image01.jpg

88kB

rnd_me

temp is not an array, its a dom collection.

i don't think you can make one on your own, but then again, why on earth would you want a slow feature-less array?

jens1701

he thx new keyword!

I tested a little bit more and i couldn't find any differences in behavior.
Anything i need to be aware of when handling Dom Collections?

Flanagan stated that Dom api method getElementsByTagName returns the found Elements in form of an array.

So why are there differences in the firebug debig display mentioned above.´?

Greets

Jens

mrhoo

It is more common to convert a node collection to an array.

var A=[],tags=document.getElementsByTagName('dd');
A=A.slice.call(tags,0,tags.length);

A is an array of the elements in the tags node list.
You can use any array methods to manipulate the array,
but it is no longer live, as a node list is.

It is a 'snapshot' of the document at the time the array was created.

rnd_me

jens1701;1014233 wrote:
Flanagan stated that Dom api method getElementsByTagName returns the found Elements in form of an array.

So why are there differences in the firebug debig display mentioned above.´?

I don't know who Flanagan is, but they are mistaken.

None of the array methods are available on collections.

If you want use Array.map for example, you need to convert it into an array first.

mrhoo's method works in FireFox, but won't work in IE.

A cross browser method:

function obValsLen(ob){var r=[],i=0,mx=ob.length;for(var z=0;z<mx;z++){r[z]=ob[z];}return r;}

//usage example: 
array=obValsLen(document.getElementsByTagName("div"));