// JScript File
function cambia(nima, ima){
    document.images[nima].src = ima;
}

function isDate(dateStr) {
	var datePat = /^(\d{1,2})(\/|-)(\d{1,2})(\/|-)(\d{4})$/;
	var matchArray = dateStr.match(datePat); // is the format ok?

	if (matchArray == null) {
		alert("Por favor, introduzca la fecha con formato dd/mm/yyyy.");
		return false;
	}

	day = matchArray[1]; // p@rse date into variables
	month = matchArray[3];
	year = matchArray[5];

	if (month < 1 || month > 12) { // check month range
		alert("El mes debe estar entre 1 y 12.");
		return false;
	}

	var maxday = 31;

	if (month==4 || month==6 || month==9 || month==11) {
		maxday = 30;
	} else if (month == 2) { // check for february 29th
		maxday = 28;
		if (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0))
			maxday = 29;
	}

	if (day < 1 || day > maxday) {
		alert("El día debe estar entre 1 y " + maxday + ".");
		return false;
	}

	return true; // date is valid
}