Firefox ignores option selected=“selected”

Question

If you change a dropdown and refresh the page, Firefox seems to ignore the selected attribute.

Answer 1

I'm using FF 25.0.1

It ignore selected="" and selected="selected".

But if I simply try selected the option is selected.

Strange (non conformant) behaviour. I know selected is valid HTML5 and it's the shortest form, but I usually write code that also validates as wellformed XML, so that I can use any XML validation tool to check my results in a very strict way (and data exchange is very easy...)

According to W3C, these variants should be valid on boolean attributes:

HTML5:  boolAttr="" | boolAttr="boolAttr" | boolAttr
XHTML5: boolAttr="" | boolAttr="boolAttr"

I prefer the first one, as is it nearly as short as the last (not xml conformant) variant but should validate as both XHTML5 AND HTML5. So I hope, Mozilla will fix it!