risico/jsbin.ugAfUne.html

## jsbin.ugAfUne.html
<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>JS Bin</title>
</head>
<body>

</body>
</html>

## jsbin.ugAfUne.js
function isValidDate(value, userFormat) {

// Set default format if format is not provided
userFormat = userFormat || 'mm/dd/yyyy';

// Find custom delimiter by excluding
// month, day and year characters
var delimiter = /[^mdy]/.exec(userFormat)[0];

// Create an array with month, day and year
// so we know the format order by index
var theFormat = userFormat.split(delimiter);

// Create array from user date
var theDate = value.split(delimiter);

function isDate(date, format) {
var m, d, y, i = 0, len = format.length, f;
for (i; i < len; i++) {
f = format[i];
if (/m/.test(f)) m = date[i];
if (/d/.test(f)) d = date[i];
if (/y/.test(f)) y = date[i];
}
return (
m > 0 && m < 13 &&
y && y.length === 4 &&
d > 0 &&
// Check if it's a valid day of the month
d <= (new Date(y, m, 0)).getDate()
);
}

return isDate(theDate, theFormat);
}
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset=utf-8 />
	<title>JS Bin</title>
	</head>
	<body>

	</body>
	</html>
	function isValidDate(value, userFormat) {

	// Set default format if format is not provided
	userFormat = userFormat \|\| 'mm/dd/yyyy';

	// Find custom delimiter by excluding
	// month, day and year characters
	var delimiter = /[^mdy]/.exec(userFormat)[0];

	// Create an array with month, day and year
	// so we know the format order by index
	var theFormat = userFormat.split(delimiter);

	// Create array from user date
	var theDate = value.split(delimiter);

	function isDate(date, format) {
	var m, d, y, i = 0, len = format.length, f;
	for (i; i < len; i++) {
	f = format[i];
	if (/m/.test(f)) m = date[i];
	if (/d/.test(f)) d = date[i];
	if (/y/.test(f)) y = date[i];
	}
	return (
	m > 0 && m < 13 &&
	y && y.length === 4 &&
	d > 0 &&
	// Check if it's a valid day of the month
	d <= (new Date(y, m, 0)).getDate()
	);
	}

	return isDate(theDate, theFormat);
	}