js判断每个框架内的form表单个数？
1.html:
<frameset   name= "pdi "   rows= "33%,* "   frameborder= "yes "   border= "0 "   framespacing= "0 ">  
<frame   name= "aaa "     scrolling= "no "   framespacing=1   src= "2.html ">
<frame   name= "bbb "     scrolling= "no "   framespacing=1   src= "3.html ">

2.html:
<form   name= 'aaa_form '   method=post>
<input   type=button   name=input1   value= '判断 '   onclick= 'test(); '>
</form>
<SCRIPT   LANGUAGE= "JavaScript ">
function   test()   {
var   frameall=parent.pdi.getElementsByTagName( "FRAME ");
for(var   i=0;i <frameall.length;i++){
alert(frameall[i].document.forms.length);
}
}
</SCRIPT>

3.html:
<form   name= 'bbb_form '   method=post>
<input   type=button   name=input   value= '测试 '>
</form>

为什么返回值都是0？谢谢了！

------解决方案--------------------
alert(parent.frames[i].document.forms.length);