Codenames – Turn PR #1234 into "berlin.example.com"

3 months ago 7

A lightweight TypeScript library that converts any number into consistent, memorable codename from a curated word list. It's designed for use cases where human-readability is more important than collision resistance, such as generating preview URLs or readable test IDs.

// Default: uses the cities-20 word list import codename from "codenames"; codename(1234); // "london" codename(1234); // "london" (always the same) codename(5678); // "paris" codename(6789); // "berlin" // With custom words codename(1234, ["one", "two", "three"]); // "two"

🎯 Deterministic - Same input always produces the same codename
💬 Human-Readable - Memorable names instead of random strings
🚀 Zero Dependencies - Lightweight and fast with no external packages
⚡ Fast & Tiny - 50,000+ generations per second, <3KB core + ~2KB per theme
🌐 Universal Runtime - Works in Node.js, Bun, Deno, browsers, and edge runtimes
🎨 Multiple Themes - Cities, animals, colors, space, and more built-in themes
🤖 CLI Included - Generate codenames directly from your terminal

Managing preview environments can get messy. You end up tracking which PR is deployed where, maintaining state, dealing with conflicts. Here's a simpler approach: use deterministic hashing to map PR numbers to memorable names.

import codename from "codenames/cities-20"; // PR #1234 always maps to the same URL const previewUrl = `https://${codename(1234)}.example.com`; // => https://london.example.com // PR #5678 gets a different one const anotherUrl = `https://${codename(5678)}.example.com`; // => https://paris.example.com

With 20 city names, you get 20 deployment slots. No database needed. The same PR number always produces the same city name, so URLs stay consistent throughout the PR lifecycle.

Plus, it's easier to share "london.example.com" in Slack than "preview-env-1234.k8s.us-east-1.example.com".

Docker Containers: docker run --name "app-${codename(buildId)}" myapp → app-tokyo
Session IDs: vienna-support is friendlier than sess_kJ8Hg2Bx9
Feature Flags: berlin-experiment instead of experiment_42
Test Data: Generate predictable usernames (cat, dog, bird)

// Default: uses cities-20 word list import codename from "codenames"; // OR import { codename } from "codenames"; const name = codename(1234); // "london"

You can import specific themed word lists:

// Import from a specific theme import codename from "codenames/animals-20"; // OR import { codename } from "codenames/animals-20"; const name = codename(1234); // "cat"

For maximum flexibility, use the core function with your own words:

// Use your own custom word list import { codename } from "codenames/core"; const name = codename(1234, ["alpha", "beta", "gamma"]); // "beta"

Default API (with cities-20)

import codename from "codenames"; // default export import { codename } from "codenames"; // named export codename(input: number, words?: readonly string[]): string

input - The number to convert
words - Optional array of words to use (defaults to cities-20)

Core API (with custom words)

import codename from "codenames/core"; // default export import { codename } from "codenames/core"; // named export codename(input: number, words: readonly string[]): string

input - The number to convert
words - Required array of words to use

import codename from "codenames/cities-20"; // default export import { codename } from "codenames/animals-50"; // named export // ... and many more codename(input: number): string

All APIs support the same input types:

Positive integers: 123, 1234
Negative integers: -42
Decimals: 3.14 (converted to integers internally)
Large numbers: up to Number.MAX_SAFE_INTEGER

Supported list sizes are 10, 20, 30, 50, and 100. The default theme uses 20 words.

Generate codenames directly from your terminal without writing any code.

# Generate a codename using the default cities-20 theme npx codenames 1234 # => london # Use the short alias npx cn 1234 # => london

For frequent use, install globally:

npm install -g codenames # Now you can use it without npx codenames 1234

# Choose a different theme codenames 1234 --theme animals-50 # => cat # Use short flag codenames 1234 -t colors-10 # => blue # Show help codenames --help # Show version codenames --version

# Generate deployment URLs echo "Preview: https://$(codenames $PR_NUMBER).preview.example.com" # => Preview: https://london.preview.example.com # Name Docker containers docker run --name "app-$(codenames $BUILD_ID)" myapp:latest # Create test data for i in {1..5}; do echo "User: $(codenames $i -t animals-20)" done # => User: cat # => User: dog # => User: bird # => User: fish # => User: cow

Each theme is available in multiple sizes: 10, 20, 30, 50, and 100 words. Choose based on your collision tolerance needs.

Adjectives: good, bad, big, small, new, old, hot, cold, fast, slow, ...
Animals: cat, dog, fish, bird, cow, pig, bee, ant, bat, fly, ...
Cities: paris, london, rome, tokyo, berlin, madrid, sydney, moscow, cairo, dubai, ...
Clothing: shirt, jeans, shoe, hat, sock, dress, coat, belt, tie, pants, ...
Colors: red, blue, green, yellow, black, white, gray, pink, orange, purple, ...
Countries: china, japan, india, france, italy, spain, canada, mexico, brazil, germany, ...
Elements: gold, iron, lead, zinc, tin, copper, silver, carbon, oxygen, helium, ...
Emotions: love, hate, joy, sad, fear, mad, happy, angry, glad, calm, ...
Food: bread, milk, egg, rice, meat, fish, cake, apple, cheese, pasta, ...
Gems: ruby, pearl, jade, opal, amber, diamond, emerald, gold, silver, topaz, ...
Nature: tree, sun, sky, rain, moon, star, wind, sea, water, rock, ...
Snacks: chips, nuts, cookie, pretzel, popcorn, candy, fruit, cheese, cracker, yogurt, ...