Monthly Salary Calculator

A Node.js-based library and CLI tool to calculate monthly, six-month, and yearly salaries based on hourly rate, working hours per day, and public holidays.

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Features

• Fetches public holidays dynamically using the Nager.Date API.
• Calculates working days in a month, excluding weekends and holidays.
• Computes monthly, first six-month, and yearly salaries.
• Simple CLI interface and reusable library functions.

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Installation

Clone the Repository

git clone https://github.com/briandiaz/monthly-salary-calculator.git
cd monthly-salary-calculator

Install Dependencies

npm install

Build the Project

npm run build

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Usage

As a CLI Tool

1. Build the project:

   npm run build

2. Start the CLI:

   npm start

The CLI will guide you through entering your hourly rate, working hours per day, and country code to fetch holidays. It will then display a breakdown of monthly salaries.

As a Library

You can use the functions provided by the library programmatically in your project.

Example:

const {
  fetchHolidays,
} = require("monthly-salary-calculator/dist/lib/holidays");
const {
  calculateMonthlySalaries,
} = require("monthly-salary-calculator/dist/lib/calculate");

(async () => {
  const holidays = await fetchHolidays("US", 2025); // Replace "US" with your country code
  const results = calculateMonthlySalaries(2025, 25, 8, holidays); // Hourly rate: $25, 8 hours/day
  console.table(results.monthlySalaries);
  console.log("First 6-month salary:", results.sixMonthSalary);
  console.log("Yearly salary:", results.yearlySalary);
})();

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Project Structure

monthly-salary-calculator/
├── src/
│   ├── cli.ts            # CLI implementation
│   ├── lib/
│   │   ├── holidays.ts   # Holiday fetching logic
│   │   ├── calculate.ts  # Salary calculation logic
│   │   └── prompts.ts    # CLI prompts
├── dist/                 # Compiled JavaScript files
├── scripts/              # Utility scripts (e.g., post-build fixes)
├── .gitignore            # Git ignore rules
├── package.json          # Project metadata and scripts
├── tsconfig.json         # TypeScript configuration
└── README.md             # Documentation

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Configuration

TypeScript

The project uses TypeScript with the following settings:

• target: ES2020
• module: CommonJS
• strict: Enabled for robust type-checking

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Development

Start Development Server

Run the TypeScript compiler in watch mode:

npm run dev

Build for Production

Compile the TypeScript files:

npm run build

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API Reference

fetchHolidays(countryCode: string, year: number): Promise<string[]>

Fetches an array of public holidays for the specified country and year.

• Parameters:

  • countryCode: ISO 3166-1 alpha-2 country code (e.g., "US" for United States).
  • year: Year to fetch holidays for (e.g., 2025).

• Returns: Promise<string[]> – Array of holiday dates as strings.

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calculateMonthlySalaries(year: number, hourlyRate: number, hoursPerDay: number, holidays: string[]): { monthlySalaries: Array<{ month: string, workingDays: number, monthlySalary: number }>, yearlySalary: number, sixMonthSalary: number }

Calculates monthly, first six-month, and yearly salaries.

• Parameters:
  • year: Year to calculate salaries for (e.g., 2025).
  • hourlyRate: Hourly rate in your currency.
  • hoursPerDay: Number of working hours per day.
  • holidays: Array of holidays to exclude from working days.

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Acknowledgements

• Nager.Date API for providing public holiday data.
• Node.js and TypeScript for powering this project.

Author: Brian Díaz

Feel free to reach out for collaboration or questions!

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Contributions

Contributions are welcome! Feel free to fork this repository and submit a pull request with improvements.