How to Validate an IP address using Javascript

How to Validate an IP address using Javascript

IP address validation using javascript

IP address validation

Every computer connected to the Internet is identified by a unique four-part string, known as its Internet Protocol (IP) address. An IP address consists of four numbers (each between 0 and 255) separated by periods. The format of an IP address is a 32-bit numeric address written as four decimal numbers (called octets) separated by periods; each number can be written as 0 to 255 (e.g., to

Example of valid IP address


Example of invalid IP address

  • 210.110 – must have 4 octets
  • 255 – must have 4 octets
  • y.y.y.y – the only digit has allowed
  • 255.0.0.y – the only digit has allowed
  • 666.10.10.20 – digit must between [0-255]
  • 4444.11.11.11 – digit must between [0-255]
  • 33.3333.33.3 – digit must between [0-255]

JavaScript code to validate an IP address

function ValidateIPaddress(ipaddress) 
 if (/^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/.test(myForm.emailAddr.value))
    return (true)
alert("You have entered an invalid IP address!")
return (false)

Explanation of the said Regular expression (IP address)

Regular Expression Pattern :


This is image title

Note: Last two parts of the regular expression is similar to above.

Syntax diagram - IP-address validation:

Syntax diagram - IP-address validation

Let apply the above JavaScript function in an HTML form.


<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<title>JavaScript form validation - checking IP address/title>
<link rel='stylesheet' href='form-style.css' type='text/css' />
<body onload='document.form1.text1.focus()'>
<div class="mail">
<h2>Input an IP address and Submit</h2>
<form name="form1" action="#"> 
<li><input type='text' name='text1'/></li>
<li class="submit"><input type="submit" name="submit" value="Submit" onclick="ValidateIPaddress(document.form1.text1)"/></li>
<script src="ipaddress-validation.js"></script>

JavaScript Code

function ValidateIPaddress(inputText)
 var ipformat = /^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/;
 return true;
 alert("You have entered an invalid IP address!");
 document.form1.text1.focus();return false;


Flowchart : JavaScript - ipaddress validation

CSS Code

li {list-style-type: none;
font-size: 16pt;
.mail {
margin: auto;
padding-top: 10px;
padding-bottom: 10px;
width: 400px;
background : #D8F1F8;
border: 1px soild silver;
.mail h2 {
margin-left: 38px;
input {
font-size: 20pt;
input:focus, textarea:focus{
background-color: lightyellow;
input submit {
font-size: 12pt;
.rq {
color: #FF0000;
font-size: 10pt;

Thank for reading !

Javascipt html css ip webdev

Bootstrap 5 Complete Course with Examples

Bootstrap 5 Tutorial - Bootstrap 5 Crash Course for Beginners

Nest.JS Tutorial for Beginners

Hello Vue 3: A First Look at Vue 3 and the Composition API

Building a simple Applications with Vue 3

Deno Crash Course: Explore Deno and Create a full REST API with Deno

How to Build a Real-time Chat App with Deno and WebSockets

Convert HTML to Markdown Online

HTML entity encoder decoder Online

An Introduction to HTML & CSS

At the heart of any general website or web page are lines of code in HTML and CSS. HTML, the web development language to render content and CSS, which styles the content.

The Ultimate Guide to Web Development with HTML and CSS

The Ultimate Guide to Web Development with HTML and CSS. Learn Web Development by creating a Blog with HTML and CSS. Make a web applications using HTML5 and CSS3. Create a blog from Scratch.

Know Everything About HTML With HTML Experts

HTML Assignment Help Australia @30% OFF from Sample Assignment, with Our Best HTML assignment help experts. Get HTML homework help online at affordable price. 100% Plag free assignment solution.

Animate Any SVG icons with CSS Only | SVG Stroke Animation With Html CSS

Animate Any SVG icons with CSS Only | SVG Stroke Animation With Html CSS

HTML And CSS Tutorial For Beginners | Complete HTML & CSS Course In One Tutorial

In this video you will learn basics of HTML and CSS from beginning. This HTML and CSS course is best for Beginners to start learning web design and web development. In this HTML and CSS Beginners tutorial we will discuss all the important HTML tags, CSS properties to design the website with some example and explanation. We will also learn about animation using CSS.