otp-random-generator/README.md

generate the opt 4-digit and 6-digit

# OTP Generator

A simple utility for generating random One-Time Passwords (OTPs) in JavaScript. Generates a random OTP of the specified length. It is designed to be simple and efficient, making it easy to integrate into your applications.

## Features
- **Generates Numeric OTPs**: The generated OTPs consist of numeric digits only.
- **Customizable Length**: You can specify the length of the OTP, with a default value of `6`.
- **Simple and Easy to Use**: The function is straightforward to integrate into your applications.
- **Handles Invalid Inputs Gracefully**: The function throws an error for invalid lengths, ensuring robust error handling.


## Installation

To use this utility, you can simply copy the code into your project. If you are using Node.js, you can create a module as follows:


```bash
npm install otp-random-generator
```


## Usage
Import the module in your Node.js project:
```
const { generateOTP } = require('otp-random-generator');
```

#### Generate a 6-digit OTP (default length)
```
const otp6 = generateOTP();
console.log('6-digit OTP:', otp6);
```

#### Generate an 8-digit OTP
```
const otp8 = generateOTP(8);
console.log('8-digit OTP:', otp8);
```

#### Generate a 4-digit OTP
```
const otp4 = generateOTP(4);
console.log('4-digit OTP:', otp4);
```

## Example Output
```
6-digit OTP: 394857
8-digit OTP: 48392057
4-digit OTP: 1204
```

## Function: `generateOTP`
### Description
The `generateOTP` function generates a random OTP of the specified length. It is designed to be simple and efficient, making it easy to integrate into your applications.

### Parameters
- `length` (number): The length of the OTP to generate. The default value is `6`. The length must be a positive integer.

### Returns
- A string representing the generated OTP.

### Throws
- An error if the `length` is less than or equal to `0`.