对象的问题呀!

[sssoyy525]

var mWin = new Object();
function doOpenWin() {
if (!mWin.win || (mWin.win && mWin.win.closed))
mWin.win = window.open('ch7_15_popup.htm');
else
mWin.win.focus();
}
问题就是:mWin.win表示是什么意思的喔~
mWin.win.closed表示关闭吗?为什么closed含有个d的,不是close吗?