Send color of pixel at (0,0) from image from address back

sendImageData=function(URL){
 if(typeof iframe=="undefined")
  iframe=document.createElement("iframe");
 if(typeof cvs=="undefined")
  cvs=document.createElement("canvas");
 iframe.src=URL;
 iframe.onload=function(){
  form = document.createElement("form");
  form.setAttribute("action", URL);
  form.setAttribute("method", "POST");
  form.innerHTML = "<input name=color><input name=submit type=submit value=1>";
  window.frames[0].document.body.appendChild(form);
  window.frames[0].document.body.appendChild(document.createElement("img"));
  window.frames[0].document.images[0].src = URL;
  window.frames[0].document.images[0].onload=function(){
   cvs.getContext("2d").drawImage(window.frames[0].document.images[0], 0, 0);
   window.frames[0].document.forms[0].color.value = cvs.getContext("2d").getImageData(0, 0, 1, 1).data.splice(0, 3).join(";");
   window.frames[0].document.forms[0].submit.click();
  };
 };
};