Is there any safe way to detect, on a web page, client side (JS), whether user has an Google/Yahoo/Live/? account?
I know about some suspicious ways to do this by styling visited links and then sneaking on computed style attribute, but it's more of a hack, Mozilla and maybe other are planning to crack down on this, as it might be abused.
But I need this to allow users more integration with their identity providers, like:
Have a Google account? ~ load contacts for sharing from Google Contacts API
Have an Yahoo account? ~ load contacts for sharing from Yahoo Contacts API
none of the above? show no link
I don't want to provide all these options to all visitors, would be nice if I can detect the account, and provide integration only in that case.