Ben Nadel
On User Experience (UX) Design, JavaScript, ColdFusion, Node.js, Life, and Love.
I am the chief technical officer at InVision App, Inc - a prototyping and collaboration platform for designers, built by designers. I also rock out in JavaScript and ColdFusion 24x7.
Meanwhile on Twitter
Loading latest tweet...
Ben Nadel at CFUNITED 2010 (Landsdown, VA) with:

jQuery Demo: Working With XML Documents

By Ben Nadel on

As we learn about AJAX (Asynchronous Javascript and XML), our first thought is that it is very cool. Our second thought is usually that XML sucks and it's such a pain in the butt to work with. With that discovery, many of us turn to using AJAX purely as a text/HTML delivery system or we switch to using JSON (Javascript Object Notation) which is infinitely easier to work with on the client. And, while I tend to go with JSON for my AJAX functionality, let's not forget that XML is a very cool delivery format.

If you have to use XML, you might want to consider using jQuery as well. It's very rare that you see any examples of jQuery being used with XML, but the fact is, all the features that make jQuery so amazing for XHTML traversal and searching also hold true for XML documents. The jQuery factory method ($) can take, as one of it many data types, an XML document object model. Once you do this, you can pretty much use the resultant jQuery stack as if it were an XHTML document object model (which should make you much more comfortable).

To demonstrate this, let's set up a rather simple ColdFusion page that just returns some XML data to an AJAX request:

  • <!--- Build the XML into a ColdFusion XML document. --->
  • <cfxml variable="xmlGirl">
  •  
  • <person type="girl">
  •  
  • <head>
  • <eyes value="brown" />
  • <hair value="brown" />
  • </head>
  •  
  • <torso>
  • <bust value="34A" />
  • <navel value="pierced" />
  • </torso>
  •  
  • <legs>
  • <waist value="24" />
  • <hips value="36" />
  • <calves value="22" />
  • </legs>
  •  
  • </person>
  •  
  • </cfxml>
  •  
  •  
  • <!--- Convert XML to a string. --->
  • <cfset strGirlXml = Trim( ToString( xmlGirl ) ) />
  •  
  •  
  • <!---
  • Set the length of the content. This will help the browser
  • know when the request is completel.
  • --->
  • <cfheader
  • name="content-length"
  • value="#Len( strGirlXml )#"
  • />
  •  
  • <!---
  • Set the XML document type. This will help the AJAX calling
  • program to determine which type of data is being returned
  • (XML, JSON, Script, etc).
  • --->
  • <cfcontent
  • type="text/xml"
  • variable="#ToBinary( ToBase64( strGirlXml ))#"
  • />

Notice that we are building the XML document using ColdFusion CFXml tags. We could have easily done this same task using ColdFusion's CFSaveContent tag for buffered output, but I think there is something nice about using CFXml to ensure that only proper XML structures are created. This ColdFusion XML document is then converted to a string and streamed back to the client.

Ok, now that we have our XML feed set up (girl.xml.cfm), let's create the HTML page that will consume this data:

  • <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  • <html>
  • <head>
  • <title>jQuery Demo: Using jQuery With XML</title>
  •  
  • <!-- Linked files. -->
  • <script type="text/javascript" src="jquery-latest.pack.js"></script>
  • <script type="text/javascript">
  •  
  • // This function will handle the xml Onload event
  • // handler. It will be passed the XML data object
  • // and the status of the XmlHttpRequest object.
  • function XmlOnLoad( xmlData, strStatus ){
  • // Let's start out by converting the XML data
  • // returned by the AJAX request into a jQuery
  • // XML document object model.
  • var jData = $( xmlData );
  •  
  • // Get the person object (but only if it is a girl).
  • var jGirl = jData.find( "person[ type = 'girl' ]");
  •  
  • // Get the direct children of the girl. These
  • // will represent the sections of the body.
  • var jSections = jGirl.children();
  •  
  • // For each of the section, we want to create
  • // an element in the girl definition list. Get a
  • // pointer to said definition list.
  • var jList = $( "#girl" );
  •  
  •  
  • // For each section, create a list item.
  • jSections.each(
  • function( intSectionIndex ){
  • var jSection = $( this );
  • var jTerm = $( "<dt></dt>" );
  •  
  • // Set the term text.
  • jTerm.text( jSection[ 0 ].nodeName );
  •  
  • // Append term to list.
  • jList.append( jTerm );
  •  
  •  
  • // Now, for each part of the section, we are
  • // going to need to create a list.
  • jSection.children().each(
  • function( intPartIndex ){
  • var jPart = $( this );
  • var jDef = $( "<dd></dd>" );
  •  
  • // Set the DD text.
  • jDef.text(
  • " - " +
  • jPart[ 0 ].nodeName + ": " +
  • jPart.attr( "value" )
  • );
  •  
  • // Append to list.
  • jList.append( jDef );
  • }
  • );
  • }
  • );
  • }
  •  
  •  
  • // When the document has loaded, request the girl
  • // XML object which will then use to populate the
  • // XHTML document.
  • $(
  • function(){
  • $.get(
  • "girl.xml.cfm",
  • {},
  • XmlOnLoad
  • );
  • }
  • );
  •  
  • </script>
  • </head>
  • <body>
  •  
  • <h1>
  • jQuery Demo: Using jQuery With XML
  • </h1>
  •  
  • <dl id="girl"></dl>
  •  
  • </body>
  • </html>

This code looks complicated because there are a lot of comments, but really, it's quite simple. The magic here is that in my AJAX callback method, I am taking the returned XML document and creating a jQuery stack object:

  • var jData = $( xmlData );

jData, our jQuery instance object, now contains the XML document object model (#document) which can be traversed using any of jQuery's sweet ass functions (ex. find(), children(), parent(), etc.).

The code of our page takes the XML document, which defined body parts, and uses the data to populate a Definition List. Running the above code, we get:

jQuery Demo: Using jQuery With XML

head
- eyes: brown
- hair: brown
torso
- bust: 34A
- navel: pierced
legs
- waist: 24
- hips: 36
- calves: 22

So, while raw XML can be complicated to work with, using XML in conjunction with jQuery can make things much easier. I am not advocating using this over JSON, as I think JSON is the bee's knees; but certainly, in a scenario where XML is your only option (as it might be with something like centralized input validation), jQuery is certainly something you're gonna want to check out.

Tweet This Deep thoughts by @BenNadel - jQuery Demo: Working With XML Documents Thanks my man — you rock the party that rocks the body!



Reader Comments

Thanks for the excellent article! I was trying to work out how to use jQuery with XML a few weeks back and this article clears things up perfectly! :D

@Guy,

Glad to help. Yeah, you really don't see many examples with this. Most of the time, just a footnote about "This also works with XML". So, I figured I would put this out there.

Hi Ben,

Good article. I haven't looked into JQuery yet (only CF8 Ajax functions and Spry) but it's something I do want to experiment with and this will help.

I do have a question though. Why are you converting the XML to base64 and then to binary - I couldn't figure out why that was necessary.

@James,

I do that because I find using the CFContent tag to set the type of data and stream the data quite convenient. By streaming a binary variable, the CFContent takes care of all the white space management. With an XML file, you have to be careful not to return leading white space (or at least it is best practice). By streaming the variable, you know for sure that none of the pre-page processing will cause the XML data to be malformed.

great article!
here's a quick question..
I'm very VERY new to all this...
so I'm rack my brain trying to get how ajax and jquery all work.
say if I have three buttons...each with ID 1, 2, and 3.
I have an xml file with 3 different pieces of info each with an id of 1, 2, and 3 as well. How would I make a string that takes the id of the button...matches it to the ID of the xml...then spits out the corresponding info?

Hey Ben, you saved my life. I needed to build a 3-select menu decision tree with data driven by an XML file. I thought I couldn't be able to do it using jquery, because I was googling xpath and jquery and reading a lot about how jquery not supporting xpath but this will work. Thanks.

Hi all,
When i try to parse an xml which is in string using jquery, it doesnt work with ie whereas it perfectly works in mozilla and other browsers. Can any body help me in this issue thanks in advance.

-Srini

Hi Srini

I had the same issue when I started out using this blog post from Ben - but then I got to know about this: http://dev.jquery.com/ticket/3143

Its an issue with IE in the sense that it does not recognise a string as XML when passed through the jQuery Constructor and hence will never traverse it; but in FF, the same code would work fine.

The fix for this is also given in the link I provided above.

Cheers
Sreenath

@Srinivasan, @Sreenath,

Yeah, IE has some issues parsing XML that we input manually. That link provided above by @Sreenath looks good. Rest assured, though, that IE can handle XML that comes back via AJAX (as far as I know).

Thank you for this. I'm grabbing external domain XML with PHP and passing it to JQuery as a JSON object and was going crazy trying to get it to work. The solution in the link fixed it right up!

How may I use jQuery to select processing instruction node in xml? Essentially I would like to get the value of the "href" in the "xml-stylesheet" processing instruction

<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet type="text/xsl" href="cdcatalog.xsl"?>

Hey thanks Ben..

That was a great one.
I am a starter to jQuery

Now, I created tags in xml that resemble the controls of html eg,
<Controls>
<input id="txtName" type="text" value="" maxlength="20"></input>
</Controls>

I successfully converted this to a html control using javascript.

But I want to do the same using jQuery. How would I be able to do it ??
Please advise.

Hi Ben !

Nice article! I'm having some issue with CDATA when parsing, read lot about it but cant figure out the correct way to do it (cross-browser). So if u know a work aorund it would be great !

thanks!

nico!

@Rahesh,

It might be easier to send the response back as JSON and have the "controls" key contain the HTML for the controls, rather than an XML representation of the controls. That way, you can just dump the HTML into the DOM and it should work right out of the box.

@Nico,

Hmm, I have not done too much with CDATA. For AJAX, I mostly use JSON for all of my data transfer these days (including HTML markup). It makes this much more simple in my opinion. Sorry I don't have better advice on this matter.

@Mohammed,

You'd have to post the XML back to the server and use a server-side scripting language (like ColdFusion) to save the XML back to the remote file system. There's nothing in jQuery specifically to help you do that.

Great article! Helped me out with the basics of handling xml in jQuery.

btw, this page is a top google result for "jquery xml navigation" keyword, despite the lack of the word "navigation" on this page, I guess your "screen readers" accessibility added an extra value for SEO.

Excellent article very useful.

I have a scenario where I get the XML from the server convert it to a Jquery object by
$xmlDoc= $(XMLFromServer);

Now I want to convert Jquery Object to XML and send it back to the server.

Any help much appreciated

Thanks
Suhu

Hi..
Thanks for sharing this information and resources it's really help full for me with the help of this we can improve our designs and development I really inspire with this information thanks

Thanks Ben for sharing this,

I am now able to get cross site RSS feed using JQuery, CF and FuseBox

Information on this blog is useful as always.