A short javascript function to convert an IP address in dotted decimal notation to a regular decimal. This is useful for IP address geolocation lookups. Supports both IPv4 and IPv6 addresses. http://en.wikipedia.org/wiki/Ip_address

IpToDecimal.js

// convert the ip address to a decimal
// assumes dotted decimal format for input
function convertIpToDecimal(ip) {
        // a not-perfect regex for checking a valid ip address
	// It checks for (1) 4 numbers between 0 and 3 digits each separated by dots (IPv4)
	// or (2) 6 numbers between 0 and 3 digits each separated by dots (IPv6)
	var ipAddressRegEx = /^(\d{0,3}\.){3}.(\d{0,3})$|^(\d{0,3}\.){5}.(\d{0,3})$/;
	var valid = ipAddressRegEx.test(ip);
	if (!valid) {
		return false;
	}
	var dots = ip.split('.');
	// make sure each value is between 0 and 255
	for (var i = 0; i < dots.length; i++) {
		var dot = dots[i];
		if (dot > 255 || dot < 0) {
			return false;
		}
	}
	if (dots.length == 4) {
		// IPv4
		return ((((((+dots[0])*256)+(+dots[1]))*256)+(+dots[2]))*256)+(+dots[3]);
	} else if (dots.length == 6) {
		// IPv6
		return ((((((((+dots[0])*256)+(+dots[1]))*256)+(+dots[2]))*256)+(+dots[3])*256)+(+dots[4])*256)+(+dots[5]);
	}
	return false;
}

Your regular expression fails for IPv6 addresses.

104.244.42.1