oPopup = window.createPopup()

You reveal the popup window by the show() method. Here is an example of a popup window:

<SCRIPT LANGUAGE="JavaScript">
<!--
oPopup = window.createPopup();
var oPopupBody = oPopup.document.body;
oPopupBody.style.backgroundColor = "magenta";
oPopupBody.style.border = "solid blue 3px";
oPopupBody.innerHTML = "Click outside <B>popup</B> to close.";
oPopup.show(300, 80, 200, 50, document.body);
// -->
</SCRIPT>

You send a popup window away either by clicking anywhere on the page, or by a script:

oPopup.hide();

function onOff() {
  if (on) {
    oPopup.hide();
	on = false;
  }
  else {
    oPopup.show(300, 80, 200, 50, document.body)
	on = true;
  }
}

You call this function using the setInterval() function, every 2000 milliseconds:

setInterval("onOff()", 2000);

Notice that we call demoPopup() when the page loads, and then the popup window (top right corner of the page) goes on and off every 2 seconds. Since we access oPopup from different functions, we define it as a global variable, somewhere in one of the JavaScript sections, not in any one of the functions:

var oPopup;

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