There have been a few tutorials on how to link scatter to a dapp which is just html/js, but those could be outdated due to the speed that eos has developed. What is the latest tutorial on how to link scatter or a mobile wallet to a dapp as of April 2019? What I'm interested in is how does one use their html/js application to communicate with the scatter desktop wallet and mobile wallets like Lynx/Meet.one --- How does clicking on the "login" button on the static html/js page make these wallets popup to prompt you to authorize a login?
Probably the best tutorial is to take a look at the Universal Authenticator Library - UAL and how it works.
Here are some helpful links:
There are are several different UAL-Repositories + Usage-Examples for use with the different available Wallets.