Disable navigation keys for web apps (F5, Backspace)

suppressnavkeys.js

(function(log) {

  var handler = function(evt) {
    evt = evt || window.event;
    var target = evt.target || evt.srcElement;

    // F5, backspace
    if ((evt.keyCode == 116) ||
        (evt.keyCode == 8 && !/input|textarea/i.test(target.nodeName))
     ) {
        evt.returnValue = false;
        evt.keyCode = 0;
	if (log) {
            console.log('key #'+evt.keyCode+' supressed');
        }
        return false;
    }
  }
  document.addEventListener("keydown", handler, true);
  document.addEventListener("keypress", handler, true);

})(true); // false to disable logging