https://www.plantruffe.fr/WindowAPI.js

1	function WNDAPICreateSizeAttr( sAttr, nWidth, nHeight, nXOffset, nYOffset )
2	{
3		var nLeft, nTop ;
4		if ( navigator.appName == "Netscape" )
5		{
6			nLeft = window.screenX + ((window.outerWidth - nWidth) / 2);
7			nTop = window.screenY + ((window.outerHeight - nHeight) / 2);
8		}
9		else
10		{
11			nLeft = (screen.width - nWidth) / 2;
12			nTop = (screen.height - nHeight) / 2;
13		}
14		if ( nXOffset != null ) nLeft += nXOffset ;
15		if ( nYOffset != null ) nTop += nYOffset ;
16		if ( sAttr.length > 0 ) sAttr += ","
17		return( sAttr + "left=" + nLeft + ",top=" + nTop + ",width=" + nWidth + ",height=" + nHeight );
18	}
19
20	function WNDAPIOpenWindow( sWndName, sURL, sWndStyle, nWidth, nHeight, nXOffset, nYOffset )
21	{
22		if ( sWndName == null )	sWndName = "WNDAPI" ;
23		if ( (nWidth != null) && (nHeight != null) )
24			sWndStyle =  WNDAPICreateSizeAttr( sWndStyle, nWidth, nHeight, nXOffset, nYOffset );
25		var objWin = window.open( sURL, sWndName, sWndStyle );
26		if (objWin.focus) objWin.focus();
27	}