Je n'avais pas vu ce bug...
<html>
<head>
<script>
function tester()
{
var champ=document.f.ch.value
if(champ.length==10)
{ if((champ.substring(0,4)<9999)&&(champ.substring(4,5)=="/")&&(champ.substring(5,7)<13)&&(champ.substring(7,8)=="/")&&(champ.substring(8,10)<99)&&(champ.substring(10,10)==""))
{
alert("bon")
}
}
}
</script>
</head>
<body>
<form name="f">
<input type="text" size="21" name="ch" value="Votre date (aaaa/mm/jj)">
<input type="button" onclick="tester()" value="test">
</form>
</body>
</html>
Jsman 