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JavaScript - Check if a String is a Valid IP Address Format

Last Updated : 05 Aug, 2025
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An IP address is a unique identifier assigned to each device connected to a computer network that uses the Internet Protocol for communication. There are two common types of IP addresses: IPv4 and IPv6. In this article, we’ll explore how to check if a string is a valid IP address format in JavaScript.

Using Regular Expressions

This approach uses regular expressions to match valid IPv4 and IPv6 patterns.

JavaScript 
function checkIp(ip) {
    const ipv4 = 
        /^(\d{1,3}\.){3}\d{1,3}$/;
    const ipv6 = 
        /^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$/;
    return ipv4.test(ip) || ipv6.test(ip);
}
const ipAddress = "122.0.0.0";
console.log(checkIp(ipAddress));

Output
true

Using Split and Validate

This approach splits the string by periods or colons and validates each part individually.

JavaScript 
function validIp(ip) {
    const parts = ip.split(/[.:]/);

    if (parts.length === 4) {

        // Check IPv4 parts
        for (const part of parts) {
            const num = parseInt(part);
            if (isNaN(num) || num < 0 || num > 255) {
                return false;
            }
        }
        return true;
    } else if (parts.length === 8) {

        // Check IPv6 parts
        for (const part of parts) {
            if (!/^[0-9a-fA-F]{1,4}$/.test(part)) {
                return false;
            }
        }
        return true;
    }
    return false;
}

const ipAddress = "2001:0db8:85a3:0000:0000:8a2e:0370:7334";
console.log(validIp(ipAddress));

Output
true

Using Library Functions

There are some libraries available in JavaScript that make IP address validation easier. One popular library is ip-address. This library helps to easily check whether an IP address is valid.

First, install the library

npm install ip-address
JavaScript 
const ip = require('ip-address');

function checkIp(ipAddress) {
    try {
        const parsed = new ip.Address6(ipAddress);
        return parsed.isValid() || new ip.Address4(ipAddress).isValid();
    } catch (e) {
        return false;
    }
}
const ipAddress = "192.168.1.1";
console.log(checkIp(ipAddress));

Output

true

Using 'net' module (Node.js specific)

If you are using Node.js, you can use the built-in net module to check if an IP address is valid. The net module provides functions like is IPv4() and is IPv6() to check if the address is valid.

JavaScript 
const net = require('net');

function isValidIp(ipAddress) {
    // For IPv4
    if (net.isIPv4(ipAddress)) {
        return true;
    }

    // For IPv6
    if (net.isIPv6(ipAddress)) {
        return true;
    }

    return false;
}

const ipAddress = "192.168.1.1";
console.log(isValidIp(ipAddress));

Output
true

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