Notice while on Google\'s homepage, with no focus on any element, pressing BACKSPACE will put the focus into the search toolbar instead of navigating back.
How can I
This is old, but these answers will still allow you to backspace and navigate when focused on a radio button. You will want to filter the input type as well. Credit to all answers above for this:
$(document).on("keydown", function (e) {
if (e.which === 8 && !$(e.target).is("input[type='text']:not([readonly]), textarea")) {
e.preventDefault();
}
});