function chiffres(event)
{
    // Compatibilité IE / Firefox
	if(!event&&window.event) {
		event=window.event;
	}
	// IE
	if((event.keyCode < 48 || event.keyCode > 57) && (event.keyCode != 127) && (event.keyCode != 13)) {
		event.returnValue = false;
		event.cancelBubble = true;
	}
	// DOM
	if((event.which < 48 || event.which > 57) && (event.which != 8) && (event.keyCode != 13)) {
		event.preventDefault();
		event.stopPropagation();
	}
}

function ChangeQt(IdElem, action)
{

    Qt = document.getElementById('Qt'+IdElem).value ;
	
	if (action == 'plus') {

		    Qt ++ ;
			document.getElementById('Qt'+IdElem).value = Qt ;
			document.getElementById('Quantite'+IdElem).value = Qt ;
	
	}
	
	if ((action == 'moins') && (Qt != 0)) {

		    Qt -- ;
			document.getElementById('Qt'+IdElem).value = Qt ;
			document.getElementById('Quantite'+IdElem).value = Qt ;
	
	}

}