I cannot believe this statement. Unobstrusive javascript wires up events using javascript code instead of onclick attributes in tags. If your javascript doesn't load, it can't wire up events. Obtrusive javascript would work just fine because it's embedded in an attribute (like onlick) on the tag. (Assuming javascript is turned on and the browser supports it.)
This is not what I meant at all. If you have JS, you'd see one field. No JS, you see a regular login form. It has nothing to do with onclick attributes.
Also, just because it looks like one input field, doesn't mean it has to be one input field. It could be two fields masquerading as one.
Still, I don't think this is a useful design pattern.
I cannot believe this statement. Unobstrusive javascript wires up events using javascript code instead of onclick attributes in tags. If your javascript doesn't load, it can't wire up events. Obtrusive javascript would work just fine because it's embedded in an attribute (like onlick) on the tag. (Assuming javascript is turned on and the browser supports it.)