@fimbul-works/futhark

Futhark (Old Norse for alphabet) is a tiny, zero-dependency utility for encoding and decoding numbers using configurable alphabets - with base-62 and Elder Futhark runes bundled out of the box.

Features

• ⚡ Ultra-lightweight: Negligible bundle footprint - pure arithmetic, no dependencies.
• 🔤 Alphabet-agnostic: Encode with any ordered character set you define.
• 🔢 Base-62 built-in: URL-safe, case-sensitive compact number encoding.
• ᚠ Elder Futhark built-in: Encode numbers as runic glyphs using the canonical 24-rune alphabet.
• 🔁 Fully reversible: Every encode has a matching decode - lossless round-trips guaranteed.

Installation

npm install @fimbul-works/futhark

Quick Start

Base-62 Encoding

import { encodeBase62, decodeBase62 } from '@fimbul-works/futhark';

encodeBase62(0);         // "0"
encodeBase62(62);        // "10"
encodeBase62(123456789); // "8m0Kx"

decodeBase62("8m0Kx");   // 123456789

Runic Encoding

import { encodeFuthark, decodeFuthark } from '@fimbul-works/futhark';

encodeFuthark(0);   // "ᚠ"
encodeFuthark(24);  // "ᚢᚠ"
encodeFuthark(999); // "ᚢᛒᛊ"

decodeFuthark("ᚢᛒᛊ"); // 999

Custom Alphabet

Bring your own character set for domain-specific encodings:

import { encodeNumber, decodeNumber } from '@fimbul-works/futhark';

const DNA = "ACGT";

encodeNumber(0, DNA);   // "A"
encodeNumber(255, DNA); // "TTTT"

decodeNumber("TTTT", DNA); // 255

API

encodeNumber(num, alphabet)

Encodes a non-negative integer into a string using the given alphabet.

| Parameter | Type | Description | |------------|----------|--------------------------------------| | num | number | Non-negative integer to encode | | alphabet | string | Ordered character set to encode with |

Returns string. Throws on negative input or an empty alphabet.

decodeNumber(str, alphabet)

Decodes a string back into a number using the given alphabet.

| Parameter | Type | Description | |------------|----------|--------------------------------------| | str | string | Encoded string to decode | | alphabet | string | The same alphabet used to encode |

Returns number. Throws if the string contains characters not in the alphabet.

encodeBase62(num) / decodeBase62(str)

Convenience wrappers using BASE62_ALPHABET (0–9, a–z, A–Z).

encodeFuthark(num) / decodeFuthark(str)

Convenience wrappers using FUTHARK_ALPHABET (ᚠᚢᚦᚨᚱᚲᚷᚹᚺᚾᛁᛃᛇᛈᛉᛊᛏᛒᛖᛗᛚᛜᛞᛟ).

Exported Constants

import { BASE62_ALPHABET, FUTHARK_ALPHABET } from '@fimbul-works/futhark';

License

MIT License - See LICENSE file for details.

Built with ⚡ by FimbulWorks