JS如何在子框架内设置父框架的同级框架里的属性。

<frameset rows="50,*,20" cols="*" frameborder="no" border="0" framespacing="0">
  <frame src="topframe.html" name="topFrame" frameborder="no" scrolling="No" noresize="noresize" id="topFrame" title="topFrame" />
  <frameset name="myFrame" cols="180,4,*" frameborder="no" border="0" framespacing="0">
    <frame src="bak_leftframe.html" name="leftFrame" frameborder="no" scrolling="no" noresize="noresize" id="leftFrame" title="leftFrame" />
<frame src="switchframe.html" name="midFrame" frameborder="no" scrolling="No" noresize="noresize" id="midFrame" title="midFrame" />
    <frameset rows="68,*" cols="*" frameborder="no" border="0" framespacing="0">
         <frame src="mainframe.html" name="mainFrame" frameborder="no" scrolling="no"  noresize="noresize" id="mainFrame" title="mainFrame" />
         <frame src="manframe.html" name="manFrame" frameborder="no" scrolling="no" noresize="noresize" id="manFrame" title="manFrame" />
    </frameset>
  </frameset>
  <frame src="bottomframe.html" name="bottomFrame" frameborder="no" scrolling="No" noresize="noresize" id="bottomFrame" title="bottomFrame" />
</frameset>我想在bak_leftframe.html页面里面设置bottomframe.html里面的一个文本框的值，请问如何得到bottomFrame框架页的正确路径?