关于window.open

Question

function opennew()
{
if (parent.frames.length==0)
{
var udswin=window.open("login.aspx","","toolbar=no,resizable=yes");
udswin.moveTo(0,0);
udswin.resizeTo(window.screen.availWidth,window.screen.availHeight);
}
window.opener = null;
window.close();
}为什么udswin==null呢

Answer 1

var tmp=window.open("about:blank","","fullscreen=1")
tmp.moveTo(0,0)
tmp.resizeTo(screen.width+20,screen.height)
tmp.focus()
tmp.location=owurl
function WinOpen() {
mesg=open("","DisplayWindow","toolbar=no,,menubar=no,location=no,scrollbars=no");
mesg.document.write("");
}

Answer 2

为什么要这么写呢？
window.open("login.aspx","","toolbar=no,resizable=yes,width=100px,height=50px");
直接写里面就可以