// browser identification
var _agt = navigator.userAgent.toLowerCase();
var _is_ie = ((_agt.indexOf("msie") != -1) && (_agt.indexOf("opera") == -1));
var _is_opera = (_agt.indexOf("opera") != -1);
var _is_mac = (_agt.indexOf("mac") != -1);
var _is_mac_ie = (_is_ie && _is_mac);
var _is_win_ie = (_is_ie && !_is_mac);
var _is_gecko = (navigator.product == "Gecko");

var IS = {
 agt: function() { return navigator.userAgent.toLowerCase(); },
 mac: function() { return (IS.agt().indexOf("mac") != -1); },
 opera: function() { return (IS.agt().indexOf("opera") != -1); },
 ie: function() { return ((IS.agt().indexOf("msie") != -1) && (IS.agt().indexOf("opera") == -1)); },
 ie_mac: function() { return (_is_ie && _is_mac); },
 ie_win: function() { return (_is_ie && !_is_mac); },
 gecko: function() { return (navigator.product == "Gecko"); }
};

function chargeScript(url, pere, handler) {
  if (arguments.length != 3) { handler = null; }
  try {
    var head = document.getElementsByTagName('head')[0];
    var script = document.createElement("script");
    script.type = "text/javascript";
    script.src = url;
    if (typeof handler == 'function') {
      var evt = IS.ie() ? "onreadystatechange" : "onload";
      script[evt] = handler;
    }
    head.appendChild(script);
  } catch (e) {
    alert('Il faut insérer ' + url + ' avant ' + pere);
  }
}