用button怎么关闭popup

用button如何关闭popup
javascript弹出一个popup窗口,要在这个窗口里的一个button控件click时关闭这个popup窗口,button的onclick要怎么写,如下:
<SCRIPT   LANGUAGE= "JScript ">
var   oPopup   =   window.createPopup();
function   ButtonClick()
{
        var   oPopBody   =   oPopup.document.body;
        oPopBody.id= "body1 "
        oPopBody.style.backgroundColor   =   "lightyellow ";
        oPopBody.style.border   =   "solid   black   1px ";
        oPopBody.innerHTML   =   "Click   outside   <B> popup </B>   to   close. <button   id= 'btn '   onclick= ' '> close </button> ";
        oPopup.show(screen.width/2,   screen.Height/2,   200,   50,   document.body);
}
</SCRIPT>

[解决办法]
parent.oPopup.hide();