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IE and Firefox node tree indexing differences

Posted on 2006-11-16
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Last Modified: 2008-02-01
I'm new to XML. I've found that I get different values in IE6 vs FireFox2.0 (and FF1.5) for identical traversals of my simple xml node tree.

Here's my XML file:

<?xml version="1.0" encoding="ISO-8859-1"?>
<store>
      <item iName="widget1">
            <title> Widget One </title>
            <baseprice> 35.00 </baseprice>
      </item>

      <item iName="widget2">
            <atitle> Widget Two </atitle>
            <abaseprice> 1500.00 </abaseprice>
            <repeat> x1 </repeat>
            <repeat> x2 </repeat>
            <repeat> x3 </repeat>
            <terminal> end </terminal>
      </item>

      <item iName="widget3">
            <ptitle> widget3 </ptitle>
            <pbaseprice> 8500.00 </pbaseprice>
            <repeat> y1 </repeat>
            <repeat> y2 </repeat>
            <repeat> y3 </repeat>
            <terminal> endw3 </terminal>
      </item>

</store>


And here's the relevant js code:

      var allItems = xmlDoc.getElementsByTagName("item");
      var iTitle = allItems[1].childNodes[0].nodeName;
      var iPrice = allItems[1].childNodes[1].nodeName;

The results:

In IE, iTitle = "atitle" and iPrice = "abaseprice", as expected.
In FF, iTitle = "#text" and iPrice = "atitle".


So it's behaving like it should (at least in my mind) in IE, but not in FireFox.

In any event, why do they give me different values?? Do developers have to come up with browser-specific xml node-tree code?
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Question by:Melvinivitch
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Geert Bormans earned 400 total points
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Hi Melvinivitch,

Let me start by disappointing you...
You can not blindly rely on IE and FF to do the same thing.
They don't share the same methods.
They behave differently using methods they do share
...
It is very though to create a DOM driven cross browser XML based web page.
I very often revert to XSLT if I want it to work in both browsers.

One of the issues you meet here, is the undefinedness of the XML data model ( in  a sense)
msxml (the microsoft activeX component used for dealing with XML in a browser) has a weird way of dealing with white-space only text nodes.
If an element has only child elements and white-space only text elements, the white-space nodes are considered cosmetical (they usually are)
According to the XML recommendation these white-space nodes are relevant.
So I hate to say, but IE is pragmatic, FF is correct

childNodes[0] is the nameless text node for FF (and that is correct)
childNodes[0] is the ptitle node for IE, because it ignores the whitespace

If this were your XML
<item iName="widget3"><ptitle> widget3 </ptitle><pbaseprice> 8500.00 </pbaseprice>
both parsers would respond equally

There are different ways to work around this issue:
- you could explicitely ask for a specific childnode
    something like var iTitle = allItems[1].getElementsByTagName("ptitle"); should work
- you could add a test and pick the first childnode that is not a text node

hope this helps

Cheers!

Geert
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by:Melvinivitch
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Bloody hell.
I feared something like that. Actually, I feared (though felt silly as it's so absurd) EXACTLY that. I did recall from the w3schools tutorial on xml that the model treated whitespace as relevant, but I didn't bother completely testing that as I only half-heartedly even considered it as a possible culprit because rigorously treating whitespace such as newlines and tabs as data AND some browsers doing it differently than others would be incredibly obnoxious. Furthermore, if XML is supposed to elegantly represent data, wouldn't it be beneficial for it to be as human-readable as possible?? BAH! I digress.

Thanks very much for the info and suggestions. I'm sure (unfortunately) the work-around ideas will come in handy.


This is tremendously unpleasant. I should go back to strictly being a non-web programmer...



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by:Melvinivitch
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In case anyone's still listening...

Can I avoid these browser issues by using PHP5's SimpleXML to parse my XML file on the server-side, and not have to worry about the browsers' parser differences at all?
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Expert Comment

by:Geert Bormans
Comment Utility
If you run into browser incompatibilities,
and you can solve stuff on the server,
you should do the works serverbased
so yes, go for PHPs XML support and work from the server

If you really want to stick to browser operations
you can try to stuff a layer inbetween
here is a good example of such an intermediate library
http://mochikit.com/about.html

cheers
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