3) Fingerprinting and tracking in general are heavily javascript-focused. Less common in practice (I assume), but still possible, are 4) Rowhammer or Spectre/Meltdown style attacks that break out of the permission system. Finally, there's general trickery, manipulation, and malware, like trying to embed a frame from Facebook and steal user credentials or so on (I'm fuzzy on these sorts of attacks, not an expert).