https://github.com/eibens/modulo

The mathematical modulo operation in TypeScript for Deno.
https://github.com/eibens/modulo

deno math modulo quotient typescript utility

Last synced: 11 months ago
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The mathematical modulo operation in TypeScript for Deno.

• Host: GitHub
• URL: https://github.com/eibens/modulo
• Owner: eibens
• License: mit
• Created: 2021-06-08T11:08:45.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2021-12-06T21:57:36.000Z (about 4 years ago)
• Last Synced: 2025-02-24T07:53:02.147Z (12 months ago)
• Topics: deno, math, modulo, quotient, typescript, utility
• Language: TypeScript
• Homepage:
• Size: 20.5 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# modulo

[modulo](#) implements the mathematical [modulo operation] in TypeScript for

[Deno](https://deno.land).

[![License](https://img.shields.io/github/license/eibens/modulo?color=informational)](LICENSE)

[![deno.land/x](https://img.shields.io/badge/x/modulo-informational?logo=deno&label)](https://deno.land/x/modulo)

[![Repository](https://img.shields.io/github/v/tag/eibens/modulo?label&logo=github)](https://github.com/eibens/modulo)

[![ci](https://github.com/eibens/modulo/actions/workflows/ci.yml/badge.svg)](https://github.com/eibens/modulo/actions/workflows/ci.yml)

[![codecov](https://codecov.io/gh/eibens/modulo/branch/master/graph/badge.svg?token=OV98O91EJ1)](https://codecov.io/gh/eibens/modulo)

# Motivation

JavaScript has no native support for true modulo. The `%` operator works as

modulo for positive numbers, but not negative ones. For example, `-1 % 3 = -1`

compared to `-1 mod 3 = 2`. If you need the latter, you can either use this

module, or memorize this [modulo formula for JavaScript]:

```

x mod n = ((x % n) + n) % n

```

# Usage

The `modulo` function calculates `m = x mod n`:

```ts

import { modulo } from "https://deno.land/x/modulo/mod.ts";

const x = -1;

const n = 3;

const m = modulo(x, n);

console.assert(m === 2);

```

The `quotient` function calculates `q = floor(x / n)`.

```ts

import { quotient } from "https://deno.land/x/modulo/mod.ts";

const x = -1;

const n = 3;

const q = quotient(x, n);

console.assert(q === -1);

```

The `decompose` function calculates `(q, m)`. `q`, `m`, and `n` together define

the original value `x = q * n + m`:

```ts

import { decompose } from "https://deno.land/x/modulo/mod.ts";

const x = -1;

const n = 3;

const [q, m] = decompose(x, n);

console.assert(x == q * n + m);

```

[modulo operation]: https://en.wikipedia.org/wiki/Modulo_operation

[modulo formula for JavaScript]: https://web.archive.org/web/20090717035140if_/javascript.about.com/od/problemsolving/a/modulobug.htm