[jowsie]

You should take a look at the kind of js that gets injected into most mainstream websites nowadays.

[Jonnax]

You're going to have to explain a bit more than that.

Tabs are isolated fork each other and the web browser does give a web page the kind of access to be key logging.

If you're talking about things that you type whilst the page is in active focus then it's kinda their website you're visiting.

[zemo]

attaching an event handler to a keyboard action is not the same thing as keylogging...

[zer0tonin]

If it's on all keyboard actions, then it's the same thing.

[27182818284]

Often it is this too, because of sloppy coding, not even malicious intent. I've seen people implement JavaScript easter eggs that play a funny joke, but in doing so the developers had created a keylogger by accident that was logging everything you did on the site. Again, wasn't malicious at all they didn't think about it at all.

[diggan]

Unless you're not actually logging the actions but just listening for certain combinations like "ctrl+x" or even "x"