function a2blank() {
  var aa = document.getElementsByTagName('a');
  for (var i = 0; i < aa.length; i++) {
    var a = aa.item(i);
    if ((a.getAttribute('href').match(/^http:\/\//)) ||
        (a.getAttribute('href').match(/^https:\/\//)) ||
        (a.getAttribute('href').match(/\.(jpg|jpeg|png|gif)$/))) {
       a.onclick = function() {
         window.open(this.href, '', '');
         return false;
      };
    }
  }
}