JAVASCRIPT
Validate IPv4 Addresses using Regular Expressions
Implement robust IPv4 address validation in JavaScript with a regular expression, ensuring network inputs adhere to the correct format.
function isValidIPv4(ipAddress) {
// Regex for an IPv4 address (0-255 for each octet)
// Allows single digits like 0, 1, but avoids leading zeros for multi-digit numbers like 01.
const ipv4Regex = /^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/;
return ipv4Regex.test(ipAddress);
}
// Examples:
// console.log(isValidIPv4("192.168.1.1")); // true
// console.log(isValidIPv4("10.0.0.255")); // true
// console.log(isValidIPv4("0.0.0.0")); // true
// console.log(isValidIPv4("256.0.0.1")); // false
// console.log(isValidIPv4("192.168.1")); // false
// console.log(isValidIPv4("192.168.1.1.1")); // false
How it works: This JavaScript function utilizes a complex regular expression to validate if a string represents a correctly formatted IPv4 address. It rigorously ensures that each of the four octets contains a number between 0 and 255, separated by dots, effectively preventing malformed network inputs.