<script language="javscript">
function GoTo()
{
parent.left.document.location="a.html";
parent.right.document.location="a.html";
}
</script><input type="button" value="click me" onclick="GoTo();">
function GoTo()
{
parent.left.document.location="a.html";
parent.right.document.location="a.html";
}
</script><input type="button" value="click me" onclick="GoTo();">
<frame name="left"><frame name="right">