请教JAVA前辈：在javascript中window.open("index.jsp","_parent")中，_parent参数是什么意思？

就是当前窗口的父亲窗口，当前窗口是从父窗口弹出来的，是它生的。

opener
A reference to the Window object that opened this one, or null if this window was opened by the user.

parent
If the current window is a frame, a reference to the frame of the window that contains it.

self
A self-referential property; a reference to the current Window object. A synonym for window.

top
If the current window is a frame, a reference to the Window object of the top-level window that contains the frame. Note that top is different from parent for frames nested within other frames.

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when u meet a unknow parameter of Javascript.
First step,search the web.
Second,read JavaScript.The.Definitive.Guide.4th.Edition and then write some codes to practice.
The last,go to a forum and post a new thread for your question.