window.onload = function() {

  var aArray = document.getElementsByTagName('a');

  for(var i = 0; i < aArray.length; i++) {

    if(aArray[i].className == "diapo") {
      aArray[i].onclick = opendiapo;
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}



function opendiapo() {

  var popup = window.open(this.href + "&js=1", "Diapo","height=700,width=600");
  popup.focus();
  return false;
}