var utils = {
  fixExtLinks: function() {
    var eles = document.getElementsByTagName('a');
    for (var i=0,ele=null; i<eles.length, ele=eles[i]; i++) {
      if (ele.className.indexOf('ext') > -1) ele.target = '_new';
    }
  },
  addEvent: function(ele, evt, func) {
    var prev = ele[evt];
    if (prev) {
      ele[evt] = function() {
        prev();
        func();
      }
    } else {
      ele[evt] = function() { func()}
    }
  },
  setup: function() {
    utils.addEvent( window, 'onload', utils.fixExtLinks);
  }

}
utils.setup();