Hello there Javascripters,

I saw some websites which use javascript to validate a login form. And when your username contains characters while they arent allowed you see a little popup in the same window with the requirements and with what you already did and what you have to do. So how can i make that popup?

You can also see an example at the website of league of legends, i think its leagueoflegends.com.

Thanks in advance,
Aigyptus