Edit in JSFiddle

var dnhUrl = "daynhauhoc.com";

function genPopup() {
  var popup = window.open("", "DNH", "width=300,height=100");

  if (popup) {
    popup.document.body.innerHTML = "<p>" + popup.opener.dnhUrl + "</p>";
    popup.document.title = popup.name;

    popup.opener.document.body.innerHTML = "<p>Loaded!</p>";
  } else {
    document.body.innerHTML = "<p>Not loading!</p>";
  }
}
// genPopup();

<button onclick="genPopup();">Run</button>