function checkNumber (field){
	
	field.focus();
	var chkZ = 0;
	for(i=0;i<field.value.length;++i){
		if(field.value.charAt(i) < "0"	
		|| field.value.charAt(i) > "9"){
				chkZ = 1;
		}	
	}
	if(chkZ == 1) {
		alert("This price is not a number");
		field.focus();
		return false;
	}
	
}


function chkfieldComment (comment){
	
	if(document.form[comment].value.length == 0){
		alert("You must fill the COMMENT field");
		document.form[comment].focus();
		return false;	
	}
}

function chkfieldContribute (name,description){
	
	if(document.form[name].value.length == 0){
		alert("You must fill the NAME field");
		document.form[name].focus();
		return false;	
	}
	if(document.form[description].value.length == 0){
		alert("You must fill the COMMENT field");
		document.form[description].focus();
		return false;	
	}
}

//check a checkbox
function checkThis(laCase,leFormulaire){
	window.document[leFormulaire][laCase].checked = true;
}