konami-kickass

Listen for the Konami code (↑ ↑ ↓ ↓ ← → ← → B A) and, once entered, unleash the KickAss game overlay on any page.

Install

npm install konami-kickass

Usage

import { listenForKonami } from "konami-kickass";

// Start listening. Enter the Konami code to launch KickAss.
listenForKonami();

With options:

import { listenForKonami } from "konami-kickass";

const listener = listenForKonami({
  repeat: true, // keep listening after activation
  onActivate() {
    console.log("KickAss launched!");
  },
});

// Later, stop listening:
listener.destroy();

You can also trigger it manually:

import { launchKickass } from "konami-kickass";

launchKickass();

Script tag

If you are not using a bundler, build then drop the ESM bundle into a module script:

<script type="module">
  import { listenForKonami } from "./dist/konami-kickass.js";
  listenForKonami();
</script>

Demo

A standalone page lives in examples/demo/:

npm run demo   # builds, then serves on http://localhost:8899

Open http://localhost:8899/examples/demo/ and type the Konami code. An on-screen meter tracks progress; entering the full sequence launches the game. Uncomment the assetBase line in the demo to test a proxy.

API

listenForKonami(options?)

Attaches a keydown listener and calls launchKickass() once the sequence is entered. Returns a { destroy() } handle.

| Option | Type | Default | Description | | ------------ | ------------------------ | -------------------------- | -------------------------------------------------- | | target | Window \| HTMLElement | window | Element to attach the listener to. | | sequence | string[] | Konami code | Custom key sequence (KeyboardEvent.key values). | | repeat | boolean | false | Keep listening after the first activation. | | assetBase | string | https://kickassapp.com/ | Proxy base for KickAss's own runtime assets. | | onActivate | () => void | — | Called right after KickAss launches. |

launchKickass(assetBase?)

Injects the bundled KickAss source into the page inline (no remote script fetch). Safe to call in non-DOM environments (no-op) and only injects once. Pass assetBase to proxy KickAss's runtime requests (see below).

Proxying KickAss's runtime requests

Bundling the script removes the fetch of kickass.js itself, but KickAss still loads its own assets at runtime — CSS, sprites, sounds, api.json, and postMessage iframes — all from a single base URL (https://kickassapp.com/).

That base is configurable. Point it at your own proxy:

import { listenForKonami } from "konami-kickass";

listenForKonami({
  assetBase: "https://your-proxy.example/kickass/",
});

or directly:

import { launchKickass } from "konami-kickass";

launchKickass("https://your-proxy.example/kickass/");

Your proxy must forward requests to https://kickassapp.com/ and preserve paths (e.g. /css/menustyles.css, /static/sounds/game/shot.mp3, /mysite/api.json, /hello.html). Notes:

• The base must end with a trailing slash.
• Iframe messaging uses this base as its postMessage origin, so the proxy origin must serve hello.html / intermediate_postmessage.html for the socket features to work.
• To fully self-host, mirror the kickassapp.com asset tree behind your proxy.

Ready-made proxies (Cloudflare Worker + Express) live in examples/proxy/ — deploy one and use its URL as assetBase.

How it works

It reproduces this bookmarklet, gated behind the Konami code — except the KickAss source is vendored into the package (src/kickass.vendor.js) and injected inline instead of loaded from a remote URL:

var KICKASSVERSION = "2.0";
var s = document.createElement("script");
s.type = "text/javascript";
s.text = /* bundled kickass.js source */;
document.body.appendChild(s);

Note: KickAss itself still makes its own network requests at runtime — see Proxying KickAss's runtime requests to route those. To refresh the vendored copy, replace src/kickass.vendor.js and rebuild.

License

MIT