num-ber

A Node.js package for formatting numbers with thousands separators and decimal formatting. Provides a versatile format function that allows customization of decimal limits, decimal separators, and thousands separators for precise number formatting.

Installation

npm install num-ber

Usage

const num = require('num-ber');

// Basic usage
num.format(1234567);                           // '1,234,567'
num.format(1234567.5, 2);                      // '1,234,567.50'
num.format(1234567.5, 2, '.', ',');            // '1.234.567,50'

API

format(number, [decimals], [decimalSeparator], [numberSeparator], [fallback])

Formats a number with custom separators and decimal places.

Parameters

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | number | number | required | The number to format | | decimals | number | 0 | Number of decimal places to display | | decimalSeparator | string | '.' | Character used to separate decimals (e.g., '.' or ',') | | numberSeparator | string | ',' | Character used to separate thousands (e.g., ',' or '.') | | fallback | any | null | Value to return if input is invalid instead of throwing an error |

Returns

• string: Formatted number
• Error: Throws an error if the input is not a number and no fallback is provided

Examples

Default Format

num.format(1234567);                           // '1,234,567'
num.format(0);                                 // '0'
num.format(0.0001, 0);                         // '0'

With Decimal Places

num.format(1234567.5, 2);                      // '1,234,567.50'
num.format(0, 2);                              // '0.00'
num.format(1234567.828, 2);                    // '1,234,567.83'

European Format (comma as thousands, dot as decimal)

num.format(1234.5678, 2, '.', ',');            // '1.234,57'
num.format(9876543, 0, '.', '');               // '9876543'

With Custom Separators

// No separators
num.format(9876.54321, 3, '', '');             // '9876.543'

// Custom separators
num.format(1000000, 0, '.', ' ');              // '1 000 000'

Negative Numbers

num.format(-1234567.5, 2);                     // '-1,234,567.50'
num.format(-9876.54, 0);                       // '-9,877'

Very Large Numbers

num.format(999999999999.99, 2);                // '999,999,999,999.99'

Negative Decimal Places

num.format(1234.5678, -2);                     // '1,234.57'

Error Handling with Fallback

num.format('not a number', 2, ',', '.', 'Fallback');  // 'Fallback'
num.format('invalid', 2, ',', '.', 0);                // 0

Error Handling without Fallback

try {
  num.format('invalid input');
} catch (error) {
  console.error(error.message);                // 'Invalid input: Not a number'
}

Features

• ✅ Format numbers with custom thousands separators
• ✅ Format decimal places with custom separators
• ✅ Support for negative numbers
• ✅ Support for very large numbers
• ✅ Fallback value for invalid inputs
• ✅ Rounding to specified decimal places
• ✅ No external dependencies

Testing

Run the test suite:

npm test