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From: Mattias Campe <mattiaspuntcampe@geeeemeil.com>
Newsgroups: comp.lang.javascript
Subject: Re: getElementsByClassName: BUG in JS-engine?
Date: Sun, 18 Nov 2012 14:56:39 +0100
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Op 18-11-12 12:09, Martin Honnen schreef:
> Most DOM collections are "live" collections so it is difficult iterating
> over them while manipulating them. Your loop manipulates the class of
> elements and that way the collection changes while the loop is executed
> and that leads to elements being skipped as after setting
>    alleOpvallendeAlineas[0].className
> that element is removed from the collection and the one that was at
> index 1 is now at index 0. And the next loop iteration changes
>    alleOpvallendeAlineas[1]
> which is the third element in the original collection.
>
> One way to avoid that problem is working from the end of the collection
> e.g.
>    for (var l = alleOpvallendeAlineas.length, i = l - 1; i >= 0; i--) {
>      alleOpvallendeAlineas[i].className = ...;
>    }

I wouldn't have found that explanation myself, but it all makes sense, 
once you know that :). So it's not a bug in the JS-engine after all ;).

Thank you very much for your fast and clear explanation!!

Kind regards
Mattias