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,

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.