.attr() fails with TypeError when used on foreign elements, such as SVG

[rdworth]

For foreign elements in an HTML document, the .attr() method fails for getting and setting values, as it attempts to use

//DOM HTML
var value = elem[name];
elem[name] = value;

instead of

//DOM Core
var value = elem.getAttribute(name);
elem.setAttribute(name, value);

A simple test of this, in a browser that supports foreign elements in HTML documents (must implement document.createElementNS):

var rect = document.createElementNS("http://www.w3.org/2000/svg", "rect");
rect.setAttribute('width', 100);
jQuery(rect).attr('width', 200);

In jQuery 1.4a2, this fails with TypeError: setting a property that has only a getter.

References:

•  HTML5 - Foreign Elements
•  Anne’s Weblog - HTML5: the foreign lands (mathematics and graphics)
•  Snook.ca - SnookSurvey Element Attributes in JavaScript, comment by molily
•  Snook.ca - SnookSurvey Element Attributes in JavaScript, comment by PPK
•  Snook.ca - SnookSurvey Element Attributes in JavaScript, comment by Anne van Kesteren
•  John Resig - .nodeName Case Sensitivity

[rdworth]

There is a current check in .attr() for isXMLDoc, but we need a fix that works for foreign elements in HTML documents, meaning the fix needed here cannot be based on the type of document the element is from or in, but based on whether the element is from a namespace other than HTML. Patches (including tests):

•  jQuery patch

This fixes .attr() by not using the DOM HTML method of getting and setting attributes if the element is detected to be foreign. In this case, it falls back to DOM Core's .getAttribute() and .setAttribute(). Tests included.

•  Sizzle patch

This adds a new function, isForeignElement. This is similar to isXML (isXMLDoc in jQuery), except that it's based on the namespace of the element itself, rather than the type of document it's in/from, or the way it's parsed (text/html vs. application/xhtml+xml). In the case of IE, we'll get nothing from .namespaceURI, but IE doesn't support foreign elements anyway. So in this case we fall back to using isXML. This means the function isn't defined as detecting whether an element is foreign to the document it's in, but whether the element is foreign to the HTML namespace. See tests in above commit.

References:

•  HTML5 - Foreign Elements
•  MDC - Node.namespaceURI
•  MDC - document.createElememtNS

[john]

Richard - We're going to tackle this, and a number of other XML/XHTML/XUL/SVG related issues post-1.4. Thanks for the patch!

[rdworth]

Moved jQuery patch to a feature branch:  http://github.com/rdworth/jquery/commits/svgfriendly

[snover]

Duplicate of #3116.