javascript open new window

                                    <script type="text/javascript">
var windowObjectReference = null; // global variable

function openFFPromotionPopup() {
  if(windowObjectReference == null || windowObjectReference.closed)
  /* if the pointer to the window object in memory does not exist
     or if such pointer exists but the window was closed */

  {
    windowObjectReference = window.open("http://www.spreadfirefox.com/",
   "PromoteFirefoxWindowName", "resizable,scrollbars,status");
    /* then create it. The new window will be created and
       will be brought on top of any other window. */
  }
  else
  {
    windowObjectReference.focus();
    /* else the window reference must exist and the window
       is not closed; therefore, we can bring it back on top of any other
       window with the focus() method. There would be no need to re-create
       the window or to reload the referenced resource. */
  };
}
</script>

(...)

<p><a
 href="http://www.spreadfirefox.com/"
 target="PromoteFirefoxWindowName"
 onclick="openFFPromotionPopup(); return false;"
 title="This link will create a new window or will re-use an already opened one"
>Promote Firefox adoption</a></p>

                                    window.open("LINK-HERE");

                                    <script type="text/javascript">
var windowObjectReference = null; // global variable

function openRequestedPopup(url, windowName) {
  if(windowObjectReference == null || windowObjectReference.closed) {
    windowObjectReference = window.open(url, windowName,
           "resizable,scrollbars,status");
  } else {
    windowObjectReference.focus();
  };
}
</script>

(...)

<p><a
 href="http://www.spreadfirefox.com/"
 target="PromoteFirefoxWindow"
 onclick="openRequestedPopup(this.href, this.target); return false;"
 title="This link will create a new window or will re-use an already opened one"
>Promote Firefox adoption</a></p>

                                    <script type="text/javascript">
var windowObjectReference = null; // global variable
var PreviousUrl; /* global variable that will store the
                    url currently in the secondary window */

function openRequestedSinglePopup(url) {
  if(windowObjectReference == null || windowObjectReference.closed) {
    windowObjectReference = window.open(url, "SingleSecondaryWindowName",
         "resizable,scrollbars,status");
  } else if(PreviousUrl != url) {
    windowObjectReference = window.open(url, "SingleSecondaryWindowName",
      "resizable=yes,scrollbars=yes,status=yes");
    /* if the resource to load is different,
       then we load it in the already opened secondary window and then
       we bring such window back on top/in front of its parent window. */
    windowObjectReference.focus();
  } else {
    windowObjectReference.focus();
  };

  PreviousUrl = url;
  /* explanation: we store the current url in order to compare url
     in the event of another call of this function. */
}
</script>

(...)

<p><a
 href="http://www.spreadfirefox.com/"
 target="SingleSecondaryWindowName"
 onclick="openRequestedSinglePopup(this.href); return false;"
 title="This link will create a new window or will re-use an already opened one"
>Promote Firefox adoption</a></p>

<p><a
 href="https://www.mozilla.org/support/firefox/faq"
 target="SingleSecondaryWindowName"
 onclick="openRequestedSinglePopup(this.href); return false;"
 title="This link will create a new window or will re-use an already opened one"
>Firefox FAQ</a></p>

                                    var newWin = open('url','windowName','height=300,width=300');
newWin.document.write('html to write...');