text to XML object (E4X)

[hluz]

Hi everyone.
I'm having a problem with creating a XML object from a document received
via XMLHTTPRequest.
The following code:

var x = new XML(responseText)

gives javascript error: xml is a reserved identifier.
If I remove the <?xml version="1.0"?> line from responseText before
using it, it works fine.

Any ideas?

[Martin Honnen]

hluz wrote:

It is by design as the authors of the E4X specification wanted it, the
specification for
new XML(string)
says to do the following (13.4.2):
Let x = ToXML(string)
and ToXML(string) is specified as follows (10.3.1):
Parse the concatenation of
<parent xmlns=", defaultNamespace, ">", string, "</parent>"
So that way a conforming implementation has to parse e.g.
<parent xmlns=""><?xml version="1.0"?><root /></parent>
and that is not well-formed and gives a parse error.
Thus if you want to parse a string with XML markup make sure you throw
the XML declaration away before passing the string to new XML().

A regular expression to match the XML declaration is e.g.
var xmlDeclaration = /^<\?xml version[^>]+?>/;
so you could try removing it e.g.
new XML(responseText.replace(xmlDeclaration, ''))

--

Martin Honnen
http://JavaScript.FAQTs.com/

[hluz]

Martin Honnen wrote:
> hluz wrote:

>> var x = new XML(responseText)
>>
>> gives javascript error: xml is a reserved identifier.
>> If I remove the <?xml version="1.0"?> line from responseText before
>> using it, it works fine.
>
>
> It is by design as the authors of the E4X specification wanted it, the
> specification for
> new XML(string)
> says to do the following (13.4.2):
> Let x = ToXML(string)
> and ToXML(string) is specified as follows (10.3.1):
> Parse the concatenation of
> <parent xmlns=", defaultNamespace, ">", string, "</parent>"
> So that way a conforming implementation has to parse e.g.
> <parent xmlns=""><?xml version="1.0"?><root /></parent>
> and that is not well-formed and gives a parse error.
> Thus if you want to parse a string with XML markup make sure you throw
> the XML declaration away before passing the string to new XML().
>
> A regular expression to match the XML declaration is e.g.
> var xmlDeclaration = /^<\?xml version[^>]+?>/;
> so you could try removing it e.g.
> new XML(responseText.replace(xmlDeclaration, ''))
>

Thanks for your reply Martin. Yes, removing it works fine. Just one
question: Shouldn't the xml declaration be considered a Processing
Instruction and as such be ingnored when property
XML.ignoreProcessingInstructions = true?

[Martin Honnen]

hluz wrote:

> Just one
> question: Shouldn't the xml declaration be considered a Processing
> Instruction and as such be ingnored when property
> XML.ignoreProcessingInstructions = true?

No, the XML markup is parsed as normal, only when the XML object is
built after successfully parsing the markup then processing instructions
are not included with the above setting.

[Jonas Sicking]

> Thanks for your reply Martin. Yes, removing it works fine. Just one
> question: Shouldn't the xml declaration be considered a Processing
> Instruction and as such be ingnored when property
> XML.ignoreProcessingInstructions = true?

What happens is actually exactly that. We try to parse <?xml as a
processing instruction, however since the name 'xml' is reserved you get
a parsing error.

In fact, the xml-declaration appearing at the top of a file is not a
processing instruction. If you look at a DOM created by mozilla you'll
notice that the xml-declaration does not show up as a PI. The xml spec
explicitly states this.

/ Sicking