Shouldn't prefetch trigger on focus event as well?

[tontonsb]

Currently the prefecth feature triggers on hover and touch:

addEventListener('touchstart', trigger_prefetch);
addEventListener('mousemove', handle_mousemove);

I propose it should also be invoked on focus to provide the feature to users using keyboard navigation.

Would it cause any issues?

[naz3eh]

I would like to give a try to resolve this issue