解决关闭showModalDialog窗口弹出画面问题

sTarget

String that specifies or receives one of the following values. name The name of the target window or frame. _blank Load the linked document into a new blank window. This window is not named. _media Load the linked document into the HTML content area of the Media Bar. Available in Internet Explorer 6 or later. _parent Load the linked document into the immediate parent of the document the link is in. _search Load the linked document into the browser search pane. Available in Internet Explorer 5 or later. _self Default. Load the linked document into the window in which the link was clicked (the active window). _top Load the linked document into the topmost window.

The property is read/write. The property has a default value of _self.

Expressions can be used in place of the preceding value(s), as of Microsoft® Internet Explorer 5. For more information, see About Dynamic Properties.

If there is no existing window or frame with the same name as specified in the target, a new window is opened with a name equal to the value of the target.
The window name is an optional argument in the open scripting method.

The property is read/write. The property has a default value of _self. 这句话说明默认的时候_self，为什么一定要加上后才有用呢？以后有时间再去研究吧。