Disable buttons (F12)

Question

I would disable some buttons on my HTML test page, (F12, Right-click and Ctrl-U).

My code works, but F12 seems to be enabled and, when he is active (i mean, when i press and i see the "analysis page", Ctrl-U starts to works).

I've post the JavaScript code here, for some advices:

//  DX MOUSE
//============

var message="";

function clickIE() {if (document.all) {(message);return false;}}
function clickNS(e) {if
(document.layers||(document.getElementById&&!document.all)) {
if (e.which==2||e.which==3) {(message);return false;}}}
if (document.layers)
{document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickNS;}
else{document.onmouseup=clickNS;document.oncontextmenu=clickIE;}

document.oncontextmenu=new Function("return false")


//  F12
//==========

  document.onkeypress = function (event) {
    event = (event || window.event);
    if (event.keyCode == 123) {
      // alert('No F-12');
      return false;
    }
  };


//    CTRL + U
//==============

  document.onkeydown = function(e) {
    if (e.ctrlKey &&
      (e.keyCode === 85)) {
          // alert('not allowed');
          return false;
        }
      };

P.S If i disable "alert": twice after clicking, appears popup on Mozilla and the code stops working.

Answer 1

The big question is WHY?

Why would you try to prevent normal and well-known browser behavior? If you are trying to protect your front end source, this is no way to go. Anyone above entry level knowledge would be able to bypass this.

A far simpler solution is to minify and uglyfy your JS and it's more effective. It's by no means bulletproof, someone can still decompose and figure how your code works but you made his job harder.

All interactions with back should not be protected (at least not as only means of protection) on front-end anyway, do sanitization of data and actions on the backend where you can control the environment and are sure code and data is intact.

Everything on the front is exposed, nothing is safe, treat its information like you would treat a information obtained from a shady person selling crack on a corner.

That being said, let's answer the question:

$(document).keydown(function (event) {
    if (event.keyCode == 123) { 
        return false;
    }
});

If you still insist doing this you might wanna add into function above:

    if (event.ctrlKey && event.shiftKey && event.keyCode == 73) { 
        return false;
    }

To prevent ctrl shift i

And also somewhere in that toss a prevention of contextmenu event by calling preventDefault() when it happens;