Is-number-checker NPM

is-number-checker

A lightweight utility to check if a given value is a number (with optional support for numeric strings).

🚀 Features

Zero dependencies: Lightweight and easy to integrate.
Flexible type-checking: Allows strict number validation or optional support for numeric strings.
Handles edge cases: Works correctly with Object.create(null), number objects (new Number()), and whitespace-trimmed strings.
Cross-platform: Works in Node.js, browsers, and other JavaScript environments.
ESM and CJS support: Fully compatible with modern module systems.

📦 Installation

You can install is-number-checker using your favorite package manager:

# Using pnpm
pnpm add is-number-checker

# Using npm
npm install is-number-checker

# Using yarn
yarn add is-number-checker

🌟 Usage

Here's how to use the library in your project:

Import the library

// CommonJS
const isNumber = require('is-number-checker');

// ES Modules
import isNumber from 'is-number-checker';

Basic example

console.log(isNumber(123)); // true
console.log(isNumber(-45.67)); // true
console.log(isNumber(NaN)); // false
console.log(isNumber(Infinity)); // false
console.log(isNumber(null)); // false
console.log(isNumber(undefined)); // false

// By default, string numbers are not considered valid
console.log(isNumber("123")); // false

// Allowing string numbers
console.log(isNumber("123", true)); // true
console.log(isNumber(" 3.14 ", true)); // true
console.log(isNumber("hello", true)); // false
console.log(isNumber("", true)); // false

🔧 API

`isNumber(value)`

Checks if the given value is a number.

Parameters

value (any): The value to check.
allowStringNumbers (boolean, optional, default: false): Whether to accept numeric strings as valid numbers.The value to check.

Returns

boolean: Returns true if value is a valid number; otherwise, false.

🛠️ Development

If you want to contribute or run the project locally, follow these steps:

Clone the repository

git clone https://github.com/angelabenavente/is-number-checker.git
cd is-number-checker

Install dependencies

npm install

Run tests

npm run test

Lint the code

npm run eslint

🧪 Testing

This project uses Jest for testing. To run the test suite, simply use:

npm run test

Example output:

PASS  ./index.test.js
✓ returns true for valid numbers (10 ms)
✓ returns false for non-number values
✓ handles string numbers correctly when allowed
...

Feel free to add more test cases in the test file.