to-fixed-for-real

A robust JavaScript utility to truncate numbers to a fixed number of decimal places—without rounding errors. Ideal for currency and financial calculations where precision and predictability are critical.

✨ Features

• Truncates numbers to a specified number of decimal places (no rounding)
• Handles both string and number inputs
• Accepts commas or periods as decimal separators
• Supports negative numbers
• Lightweight and dependency-free
• Fully tested with Jest

Motivation

JavaScript’s native toFixed method rounds values, which can lead to inaccuracies in financial or scientific applications. This package provides a reliable way to truncate (not round) numbers to the desired decimal places, supporting both string and number inputs, and handling commas as decimal separators.

Installation

npm install to-fixed-for-real

Usage

Basic Example

const toFixed = require('to-fixed-for-real');

console.log(toFixed(12.599, 2)); // 12.59
console.log(toFixed('982,51832', 2)); // 982.51
console.log(toFixed(10, 2)); // 10.0
console.log(toFixed(-21381923.32938989, 2)); // -21381923.32

Input/Output Table

| Input | Code Example | Output | |--------------------|-------------------------------------|---------------| | 12.599, 2 | toFixed(12.599, 2) | 12.59 | | '982,51832', 2 | toFixed('982,51832', 2) | 982.51 | | 10, 2 | toFixed(10, 2) | 10.0 | | -4.3, 2 | toFixed(-4.3, 2) | -4.3 | | 1.2345, 2 | toFixed(1.2345, 2) | 1.23 | | '10.58928', 2 | toFixed('10.58928', 2) | 10.58 | | '164252,', 2 | toFixed('164252,', 2) | 164252.0 | | 0, 2 | toFixed(0, 2) | 0 |

Edge Cases

// Handles string input with comma as decimal
console.log(toFixed('164252,', 2)); // 164252.0

// Handles string input with no decimals
console.log(toFixed('10', 2)); // 10.0

// Handles zero
console.log(toFixed(0, 2)); // 0

API

toFixed(num, floatingPoint)

| Parameter | Type | Description | |--------------- |---------------- |-----------------------------------------------------------------------------| | num | number | string | The value to truncate. Accepts numbers or strings (with . or ,). | | floatingPoint| number | The number of decimal places to keep. If omitted, all decimals are kept. |

Returns: number — The truncated value.

Behavior

• Truncates, does not round.
• Handles negative numbers and string inputs.
• Converts commas to periods for decimal separation.

Testing

This project uses Jest.

npm test

Contributing

Contributions, issues, and feature requests are welcome! Please:

• Open an issue for bugs or feature requests
• Fork the repo and submit a pull request for improvements
• Add tests for new features or edge cases

License

This project is licensed under the MIT License.

Author

nethanos