Regular expression for validating the IP Address using Javascript?

Regular expression for validating the IP Address using Javascript?
[JavaScript]

function isValidIPAddress(ipaddr) {
var re = /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/;
if (re.test(ipaddr)) {
var parts = ipaddr.split(".");
if (parseInt(parseFloat(parts[0])) == 0) { return false; }
for (var i=0; i<parts.length; i++) {
if (parseInt(parseFloat(parts[i])) > 255) { return false; }
}
return true;
} else {
return false;
}
}