js13k CLI

Command‑line tools for building and serving js13kGames projects.

Quick start

npx js13k --help

Run a specific command:

npx js13k <command>

Commands

• dev: Run the dev server with js13k defaults.

  npx js13k dev

• build: Build the project with js13k defaults (outputs to dist/).

  npx js13k build

• preview: Serve the built dist/ directory and print the local URL.

  npx js13k preview

• relay: Start a minimal WebSocket relay at /parties/relay/<room>.

  npx js13k relay

  • PORT: Set the port via the PORT env var (default: 4321).
  • Clients connect to: ws://localhost:<PORT>/parties/relay/<room>

• create: Scaffold a new project from the official examples.

  npx js13k create

  Follow the prompts to pick an example and target directory.

Help

• Global help: npx js13k --help
• Command help: npx js13k <command> --help

If ECT fails to install with npx/bunx

This CLI relies on native binaries (ECT, advzip) provided via postinstall steps (ect-bin, advzip-bin). Some runners (for example, bunx) may skip or block postinstall until the package is trusted, which can cause errors like ECT not found.

If you hit trust/permission issues, install the CLI as a dev dependency and run it via your project scripts (so installation is fully trusted first):

• npm: npm i -D js13k
• pnpm: pnpm add -D js13k
• yarn: yarn add -D js13k
• bun: bun add -d js13k

Add scripts to package.json:

{
  "scripts": {
    "js13k": "js13k",
    "dev": "js13k dev",
    "build": "js13k build",
    "preview": "js13k preview",
    "relay": "js13k relay"
  }
}

Then run:

npm run dev
# or any script above, e.g.:
npm run build
# or access the CLI directly:
npm run js13k -- --help