var win = null; function NewWindow(mypage,myname,w,h){ LeftPosition = (screen.width) ? (screen.width-w)/2 : 0; TopPosition = (screen.height) ? (screen.height-h)/2 : 0; settings = 'height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+',resizable' win = window.open(mypage,myname,settings) }