function tiret(texte) {
    if (texte.substr(texte.length-1,1) == "-") {
        document.getElementById('champ').value=texte.substr(0,texte.length-1)+ "" ;
    }
} 


function chiffres(event) {
// Compatibilité IE / Firefox
if(!event&&window.event) {
event=window.event;
}
// IE
if(event.keyCode < 48 || event.keyCode > 57) {
event.returnValue = false;
event.cancelBubble = true;
}
// DOM
if(event.which < 48 || event.which > 57) {
event.preventDefault();
event.stopPropagation();
}
}