<form name="form1">
<input type="button" onclick="ys()" value="Add"/>
<input />
</form>
<script language=JavaScript>
function ys()
{form1.insertAdjacentHTML("beforeEnd","<input type='button' value='Insert Button'/>");}
</script>
<input type="button" onclick="ys()" value="Add"/>
<input />
</form>
<script language=JavaScript>
function ys()
{form1.insertAdjacentHTML("beforeEnd","<input type='button' value='Insert Button'/>");}
</script>
<form name="form1">
<input type="button" onclick="ys(this)" value="Add"/>
<input />
</form>
<script language=JavaScript>
function ys(oTxt)
{oTxt.insertAdjacentHTML("afterEnd","<input type='button' value='Insert Button'/>");}
</script>