在带有 javascript 的 HTML 中运行 XPath 表达式 SVG

Question

I'm trying to run an xpath-expression over an svg which is embedded in html. I just cannot figure out how to set up the parameters. I want find elements that have an arbitary attribute from a given namespace. I use the following xpath expression:

var xpathexp = "//*[@*[namespace-uri()='"+this.typo7namespace+"']]";

I tested this expression and it worked as expected. this is the code to find the result set:

var result = this.svgdocument.contentDocument.evaluate( xpathexp, this.svgdocument.documentElement, null, XPathResult.ANY_TYPE, null );

Could anybody tell me, or post a link to a tutorial, how to deal with the namspaces, the namespace resolvers??

Greetings...

Answer 1

Here's the Mozilla tutorial on using XPath:https://developer.mozilla.org/en/Introduction_to_using_XPath_in_JavaScript

Here's one on writing custom namespace resolvers: https://developer.mozilla.org/en/Introduction_to_using_XPath_in_JavaScript#Implementing_a_User_Defined_Namespace_Resolver

I found these interfaces to be rather clunky, though, so I wrote an abstraction layer that would take the xpath string and a context node, and would return a regular js array. It works inside the browser and embedded in Java under Mozilla Rhino: https://svn.apache.org/repos/asf/commons/sandbox/gsoc/2010/scxml-js/trunk/src/javascript/scxml/cgf/util/xpath.js

All of the above should work in all browsers except for IE6-9.

IE6-8 does not support SVG natively, so this should be less important to your question. For completeness, though, here's a good article describing XPath support in earlier IE8, including support for resolving namespaces: http://www.nczonline.net/blog/2009/04/04/xpath-in-javascript-part-3/

Apparently, IE9 also does not include support for XPath in the browser, which is more problematic, as it does support SVG natively. Probably the best approach here is to use ActiveX to work with MSXML APIs: IE9 selectSingleNode missing from beta, how to overcome this in JavaScript?