Hi,
To replace comma with dot while typing or inserting of the number into input field, you can use Javascript solution with onKeyUp and onBlur event:
<script type="text/javascript">
function replaceComma(i) {
var val = document.getElementById(i).value;
if (val.match(/\,/)) {
val = val.replace(/\,/g, '.');
document.getElementById(i).value=val;
}
}
</script>
<input type='text' id='amount' onKeyUp="javascript: replaceComma('amount'); " onBlur="javascript: replaceComma('amount'); " />