Cannot get or set custom properties

[Evert]

First things first, I've searched for similar tickets and yes I found the one were somebody confused props with attributes. I am not making the same mistake here.

​http://jsfiddle.net/PHqS9/2/

It does work with .attr('prop', 'prop') but I don't want to add prop="prop" to the element, I just want to add prop.

[gibson042]

I found the one were somebody confused props with attributes. I am not making the same mistake here.

I'm afraid you are, because […] ​selectors target attributes, not properties. And only attributes recognized as ​boolean by the client lack a proper string value. You can, however, adopt a convention for indicating truth/falsehood and check for your expected value with [attr="<true value>"] or [attr!="<false value>"], respectively.