from1:
<script>
alert(DataList.abc.value);
</script>
<form id="MultiQuickSearchTop" method="post" runat="server">
    <iframe id="DataList" src="MultiQuickSearchMain.aspx" runat="server">
    </iframe>
</form>
MultiQuickSearchMain.aspx:
<input type=TextBox name="abc" value="123">跟form没多大关系吧~