Guard against className being null/undefined

[developit]

We're seeing this line throw when element.className is null.

[ausi]

Do you have any information about how element.className can be null? Maybe a link to a website where this happens?

[developit]

Can't seem to reproduce it outside the private case I was seeing, but className is undefined for Document, Text and Comment nodes. Also for any SVG element, it's actually an Object:

https://jsfiddle.net/developit/gsLnt0cn/

(for the SVG case you basically are forced to use getAttribute('class'), which seems like a reasonable compromise given it works on any element.

[ausi]

How about using this version then:

(element.getAttribute('class') || '').split(/\s+/).forEach(function(className) {
	foundRules = foundRules.concat(rules['.' + className] || []);
});

Does this solve your issue?

[developit]

Yup! Updated the PR.

I actually managed to catch this exception today and can confirm it's happening on SVG elements (a <g> in this case):

[ausi]

Thank you for the pull request!

I added some tests and more fixes for SVG elements.