Mudando a vírgula por ponto na hora de submeter o formulário

[Frank K Hosaka]

<script>
    function alterar(){teste.value=teste.value.replace(',','.')}
</script>
<form onsubmit=alterar()>
    <input id=teste name=teste value=0,97>
    <input type=submit>
</form>
<?php
if(isset($_GET['teste'])){echo "<br> Valor=".$_GET['teste'];}