ecs-machina

ECS-Machina

A zero-dependency TypeScript Entity-Component-System Library

Installation

npm install ecs-machina

Documentation

ECS-Machina is first and foremost a TypeScript library; it's meant to be used in TypeScript projects to take full advantage of its typing system.

I created this library to be used in TIC-80 projects, and so it has 0 dependency and is ES5-compatible. You can "install" it by copy-pasting the whole index.ts file in your own project.

World

// Create a world to hold your entities and components
const world = new World()

Components

Components must be declared through the Component() abstract factory. It returns a Component Factory, that can be used to create new components and to query the World.

// With explicit types
const Position = Component<{ x: number; y: number }>()

// With default values, and implied types
const Velocity = Component({ dx: 0, dy: 0 })

// You can also declare "tag" Components that have no attributes
const IsMonster = Component()

Entities

/*
 * Add Entities to your World
 */

// Without any component
const entityA = world.spawn()

// With one or several components
const entityB = world.spawn(
  Position({ x: 10, y: 25 }),
  Velocity({ x: 0, y: 1 })
)

// Or with the default values, if components provide them
const entityC = world.spawn(Position())

Queries & Systems

ECS-Machina does not have Systems, but has a simple query() function and a runSystems() helper.

// You can create a "system" like this, a simple function that
// takes the whole World as a parameter.
function movementSystem(world: World) {
  const entities = world.query(Position, Velocity)
  for (const [e, pos, vel] of entities) {
    console.log(`Moving entity ${e}`)

    // Component instances are correctly typed for efficient auto-completion
    pos.x += vel.dx
    pos.y += vel.dy
  }
}

function attackSystem(world: World) {
  /* ... */
}

// Call `runSystems` to execute Systems within your World context
world.runSystems(movementSystem, attackSystem)

Philosophy and goals

TypeScript First

Games built with an ECS engine have a lot of different components and systems. Strong typings (and efficient autocompletion) is an essential feature to not get lost in your own code.

Code reusability

We have a strong decoupling between the World, the Components, and the Systems. The goal is to let you write code that you can truly reuse throughout your projects.

Fast systems

The world.query() function has an efficient and transparent caching system, to provide the fastest iteration speed possible.

The trade-off is that adding/removing/updating entity is relatively slower, because the cache needs to be updated each time.

Strong unit tests

This is a work-in-progress (as ECS-Machina itself is under development), but we aim for 100% of code coverage.

Credits

This library was inspired by PECS, a PICO-8 ECS library.