ko-co

Adds support for the Konami Code; making your website automatically cool.

The Konami Code is a cheat code that appears in many video games created by Konami. The code was first used in the 1986 release of Gradius on the Nintendo Entertainment System (NES). It was further popularized in the North American release of Contra on the NES.

The Konami Code requires players to enter the following sequence using their game pad: ↑ ↑ ↓ ↓ ← → ← → B A

KoCo takes a different approach to already existing Konami Code libraries. It utilizes DOM events, bringing some nice advantages:

• It keeps the library lightweight.
• It keeps the view code agnostic of KoCo. You just register DOM event listeners.
• It allows control over what elements the user can use to trigger a Konami Code easter egg. You just register the listener to specific elements.
• It is easy to stop listening when your application needs to get serious for a moment.

This module can be treated as an ES module:

import * as koco from 'ko-co';
// or
import { addSupportForTheKonamiCode } from 'ko-co';

This module can also be treated as a CommonJS module:

const koco = require('ko-co');
// or
const { addSupportForTheKonamiCode } = require('ko-co');

To add Konami Code support you just need to call the addSupportForTheKonamiCode() method, most likely in your application entry point. For example:

koco.addSupportForTheKonamiCode(
{
    // Options...
});

You can pass some options to control how the Konami Code sequence is detected:

• requireEnterPress - Determines whether the enter key is required to conclude a Konami Code sequence. Defaults to false.
• allowedTimeBetweenKeys - The maximum amount of time (in milliseconds) to wait between key presses before sequence progress is reset. By default the user can take as long as they want.

Listening for the Konami Code is just like listening to regular DOM events:

target.addEventListener('konamicode', () =>
{
    console.log('The Konami Code has been entered. 30 more lives for you!');
});

The konamicode event bubbles and is cancelable, so event delegation works as expected.

If you want to remove support for the Konami Code completely, KoCo.addSupportForTheKonamiCode() will return a function that will do that for you:

let makeMyWebsiteBoringAgain = koco.addSupportForTheKonamiCode(
{
    // Options...
});

makeMyWebsiteBoringAgain();

This module is available through the Node Package Manager (NPM):

npm install ko-co

You can build UMD and ESM versions of this module that are both ES5 compatible and minified:

npm run build

This module also has a robust test suite:

npm test

This includes a code quality check using ESLint. Please refer to the .eslintrc files to familiar yourself with the rules.

This project is released under the MIT license.