Kaboom.js is a JavaScript library that helps you make games fast and fun!

Check out our official website!

(This README talks about kaboom v0.6, which will be released shortly. Code here won't work on previous versions. For old README look at commits before e19134e)

Examples

<script src="https://kaboomjs.com/lib/0.6.0/kaboom.js"></script>
<script type="module">

// initialize kaboom context
const k = kaboom();

// add a text of size 32 at position (100, 100)
k.add([
    k.text("oh hi", 32),
    k.pos(100, 100),
]);

// or
// k.addText("oh hi", 32, { pos: k.vec2(100, 100) });

</script>

You can paste this directly into an html file and start playing around!

to make a flappy bird movement you only need 3 lines

// init context
const k = kaboom();

// make the player game object ("mark" is a default sprite)
const birdy = k.addSprite("mark", { body: true, });

// press space to jump
k.keyPress("space", () => birdy.jump());

examples above are using helper functions (like addSprite(), addText()) as a syntax sugar for kaboom's powerful composable component system

// add an entity to the scene, with a list of component describing its behavior
const player = k.add([
    // it renders as a sprite
    sprite("mark"),
    // it has a position
    pos(100, 200),
    // it is a physical body which will fall
    body(),
    // you can easily make custom components to encapsulate certain reusable logics
    doubleJump(),
    health(8),
    // or give it tags for controlling grouped behaviors in a faster way
    "player",
    "friendly",
    // custom fields
    {
        dir: vec2(-1, 0),
        dead: false,
        speed: 240,
    },
]);

// custom components are plain functions that return an object
function health(hp) {
    return {
        // comp id
        id: "health",
        // comp dependencies
        require: [],
        // custom behaviors
        hurt(n) {
            hp -= n ?? 1;
            this.trigger("hurt");
            if (hp <= 0) {
                this.trigger("death");
            }
        },
        heal(n) {
            hp += n ?? 1;
            this.trigger("heal");
        },
        hp() {
            return hp;
        },
    };
}

// listen to custom events from a custom component
player.on("hurt", () => { ... });

// decoupled discrete logic
player.collides("enemy", () => player.hurt(1));

blocky imperative syntax for describing behaviors

// check fall death
player.action(() => {
    if (player.pos.y >= height()) {
        destroy(player);
        gameOver();
    }
});

// if 'player' collides with any object with tag "enemy", run the callback
player.collides("enemy", () => {
    player.hp -= 1;
});

// all objects with tag "enemy" will move towards 'player' every frame
action("enemy", (e) => {
    e.move(player.pos.sub(e.pos).unit().scale(e.speed));
});

keyPress("w", () => {
    player.move(vec2(0, 100)),
});

if you don't feel like using kaboom's abstraction systems, can always use it like p5.js or love2d with stateless immediate mode APIs

const k = kaboom();

// runs every frame
k.action(() => {
    // checks if is pressed last frame only
    if (k.keyIsPressed("space")) {
        doSomeThing();
    }
});

// runs every frame after update
k.render(() => {
    // immediate drawing functions
    k.drawSprite("birdy");
    k.drawText("123abc");
    k.drawRect(100, 300);
});

Usage

cdn

1. self hosted

<script src="https://kaboomjs.com/lib/0.6.0/kaboom.js"></script>

All available version tags can be found in CHANGELOG.md, or Github releases.

Special Version Tags:

• dev: current master with the newest unreleased features / fixes, expect breaking changes
• latest: latest release

2. third party

kaboom is on npm thus supported by most js lib CDN providers

<script src="https://unpkg.com/[email protected]/dist/kaboom.js"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/kaboom.js"></script>

When imported in the browser, the script will expose a global kaboom function to initialize a kaboom context, returning an object containing all the functions

const k = kaboom();

k.add();
k.keyPress(...);
k.scene(...);

You can also import all functions to the global namespace by giving a global flag

kaboom({
    global: true,
});

add();
keyPress(...);
scene(...);

Kaboom also provide ES module and commonJS module exports with .mjs and .cjs, e.g,

import kaboom from "https://kaboomjs.com/lib/0.6.0/kaboom.mjs";

npm package

$ npm install kaboom

// main.ts
import kaboom, { Vec2, GameObj, } from "kaboom";
import asepritePlugin from "kaboom/plugins/aseprite";

const k = kaboom({
    plugins: [ asepritePlugin, ],
});

function spawnBullet(p: Vec2): GameObj {
    return k.add([
        k.pos(p),
        k.sprite("bullet"),
    ]);
}

also works with cjs

const kaboom = require("kaboom");

Dev

1. npm run dev to watch & build lib
2. go to http://localhost:8000/examples
3. edit examples in examples/ to test
4. make sure not to break any existing examples

Misc

• Featured on Console 50
• Shoutout to Umayr for kindly offering the "kaboom" npm package name