@codemonument/simple-rounding

A TypeScript/JavaScript module containing reliable custom functions for rounding, ceiling, flooring, truncating and formatting floating point numbers. Works with Deno, Node.js, Bun, and browsers.

Keywords: rounding, floating-point, precision, math, decimal, ceiling, floor, truncate, typescript, javascript, deno, node, bun

Why?

Basic Problem: JS Floating Point Math is highly inaccurate. Found this thread: https://stackoverflow.com/questions/11832914/how-to-round-to-at-most-2-decimal-places-if-necessary

First best solution: Use a library with correct implementation of floating point math.

• mathjs (CAUTION: not math.js!): https://www.npmjs.com/package/mathjs

  • is basically complete, but is FAT: 732 kB, 188 kB minified
  • see https://bundlephobia.com/package/[email protected]

• decimal.js: https://www.npmjs.com/package/decimal.js

  • still 31.1 kB, 12.3kB minified
  • good: last Publish in 2022 (today: 2024-09-09)

• currency.js: https://www.npmjs.com/package/currency.js

  • 2.2kB, 1kB minified
  • no dependencies
  • BUT: only compatible with TS allowSyntheticDefaultImports: true + default import

Second best solution: Use a custom implementation of roundToPrecision
@bjesuiter original selected implementation (on 2024-09-09):
https://stackoverflow.com/questions/11832914/how-to-round-to-at-most-2-decimal-places-if-necessary#:~:text=Solution%202%3A%20purely%20mathematical%20(Number.EPSILON)

2025-07-11: refined multiple times

---

Changelog

2.0.1 - 2025-07-27

• refined examples and published files

2.0.0 - 2025-07-11

• reworked the whole implementation and added more tests and examples

1.0.0

Initial release

---

For Contributors

Deploy a new version

1. Update the version in deno.json
2. Update all examples & docs
3. Run deno task test & fix errors
4. Run deno task dry & fix errors`
5. Commit, make a tag and push the tag (will then be built by github actions)