Precise Add

A lightweight JavaScript package that adds two numbers with precise decimal arithmetic, avoiding floating-point precision errors.

The Problem

JavaScript (and most programming languages) have floating-point precision issues:

0.1 + 0.2; // returns 0.30000000000000004 ❌
0.17 + 0.2; // returns 0.37000000000000005 ❌

The Solution

const add = require("precise-add");

add(0.1, 0.2); // returns 0.3 ✅
add(0.17, 0.2); // returns 0.37 ✅

Installation

npm install precise-add

Usage

const add = require("precise-add");

// Basic usage
console.log(add(0.1, 0.2)); // 0.3
console.log(add(0.17, 0.2)); // 0.37
console.log(add(1.5, 2.3)); // 3.8

// Works with integers too
console.log(add(5, 10)); // 15

// Works with negative numbers
console.log(add(-0.1, 0.2)); // 0.1

How It Works

The package converts decimal numbers to integers by multiplying by an appropriate power of 10, performs the addition, then converts back to decimal. This avoids the floating-point precision errors inherent in binary arithmetic.

API

add(a, b)

Adds two numbers with precise decimal arithmetic.

Parameters:

• a (number): The first number
• b (number): The second number

Returns:

• (number): The precise sum of a and b

Throws:

• TypeError: If either argument is not a number or is NaN

Features

• ✅ Zero dependencies
• ✅ Lightweight (~1KB)
• ✅ Handles positive and negative numbers
• ✅ Handles integers and decimals
• ✅ Proper error handling
• ✅ Works with CommonJS and ES modules

Limitations

• Only handles addition (subtraction, multiplication, division coming soon!)
• Very large numbers may still have precision limits

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

ISC

Author

Rishi Prasad Aryal

Repository

https://github.com/rishi064/precise-add