A common place is: press Enter to submit form information, which is the same as clicking button.
<formname=form1method=postaction=>
<inputtype=textname=username><br>
<inputtype=buttonvalue=click onclick=javascript:s2()>
</form>
<script>
document.onkeydown=function(){ss()}
functionss()
{
if(event.keyCode==13)
{
alert(form1.username.value);
}
}
functions2()
{
alert(form1.username.value);
}
</script>