IE7中封闭窗口时不提示

IE7中关闭窗口时不提示function shutwin(){window.openernullwindow.open(,_self) window.close()

IE7中关闭窗口时不提示

function shutwin(){
window.opener=null;
window.open('','_self');
window.close();
}

<button onclick="shutwin();">close</button>