firefox image viewer rotate context menu.js

(function () {
  var i = document.querySelector("img"),
      r = 0,
      m = "<menu type='context' id='m'>" +
            "<menuitem label='Rotate clockwise' id='rcw'></menuitem>" +
            "<menuitem label='Rotate counter-clockwise' id='rccw'></menuitem>" +
          "</menu>";
  
  function rotateBy(d) {
    r += d;
    i.style.transition = "transform 300ms ease-out";
    i.addEventListener("transitionend", function () {
      i.style.transition = "";
    });
    i.style.transform = "rotate(" + r + "deg)";
  }
  
  i.insertAdjacentHTML("afterend", m);
  
  document.getElementById("rcw").addEventListener("click", function () {
    rotateBy(90);
  });
  
  document.getElementById("rccw").addEventListener("click", function () {
    rotateBy(-90);
  });
  
  i.setAttribute("contextmenu", "m");
})();

Cool :) http://jsfiddle.net/simevidas/Lpesc/