How to Validate Octal number in ReactJS?

The Octal numeral system is the base-8 number system which uses the digits 0 to 7. It is also known as Oct for short. The following example shows how to validate the user entered data and check whether it is valid or not using the npm module in the ReactJS application. 

Approach

To validate octal number in React we will use the validator npm package. We will pass the input number to validator.isOctal function which gives boolean output. If the number is valid the display "Is Octal Number" else return "Is Not Octal Number".

Steps to Create React App and Install Modules

Step 1: Initialize React Application

Create a React application using the following command:

npx create-react-app foldername

Step 2: Switch to the Project Directory

After creating your project folder i.e. foldername, move to it using the following command:

cd foldername

Step 3: Install Required Module

After creating the ReactJS application, Install the validator module using the following command:

npm install validator

Project Structure:

It will look like the following.

The updated dependencies in package.json file are:

"dependencies": {
    "@testing-library/jest-dom": "^5.17.0",
    "@testing-library/react": "^13.4.0",
    "@testing-library/user-event": "^13.5.0",
    "react": "^18.3.1",
    "react-dom": "^18.3.1",
    "react-scripts": "5.0.1",
    "validator": "^13.12.0",
    "web-vitals": "^2.1.4"
},

Example: This example demonstrates octal number validation with the help of validator npm package.

// Filename - App.js

import React, { useState } from "react";
import validator from "validator";

const App = () => {
	const [errorMessage, setErrorMessage] = useState("");

	const validate = (value) => {
		if (validator.isOctal(value)) {
			setErrorMessage("Is Octal Number");
		} else {
			setErrorMessage("Is Not Octal Number");
		}
	};

	return (
		<div
			style={{
				marginLeft: "200px"
			}}
		>
			<pre>
				<h2>Validating Octal Number in ReactJS</h2>
				<span>Enter Number: </span>
				<input
					type="text"
					onChange={(e) => validate(e.target.value)}
				></input>
				<br />
				<span
					style={{
						fontWeight: "bold",
						color: "red"
					}}
				>
					{errorMessage}
				</span>
			</pre>
		</div>
	);
};

export default App;

Step to Run Application:

Run the application using the following command from the root directory of the project:

npm start

Output: