@tammergard/robber

Convert to and from robber language (Swedish: rövarspråket).

# npm
npm install @tammergard/robber

# pnpm
pnpm add @tammergard/robber

# bun
bun add @tammergard/robber

import { fromRobber, pattern, toRobber } from "@tammergard/robber"

toRobber("Hej") // "Hohejoj"
fromRobber("Hohejoj") // "Hej"

pattern.test("Hohejoj") // true
pattern.test("Hohej") // false

Encodes a string into robber language: every consonant is replaced with the consonant + "o" + the same consonant. The letter x is first expanded to ks (since x is pronounced "ks" in Swedish), so "yxa" becomes "ykoksosa". Vowels, digits, punctuation and other characters pass through unchanged.

Throws if the input is not a string.

Decodes a robber language string back to plain text by reversing the consonant-doubling rule. Throws if the input is not a string or not a valid robber language string.

Note that the x → ks step in toRobber is lossy, so the round trip is not perfectly reversible:

toRobber("yxa") // "ykoksosa"
fromRobber("ykoksosa") // "yksa", not "yxa"

This is by design: "x" and "ks" both encode to the same robber output, so there's no way for fromRobber to tell them apart.

A regular expression that matches valid robber language strings. A string is valid if every consonant is immediately followed by "o" + the same consonant (case-insensitive on the trailing one), and no standalone x or X appears.

MIT