Component

Base class for all components.

Components are the primary authoring model. Game developers write behavior in components using optional update(dt) and fixedUpdate(dt) methods. The built-in ComponentUpdateSystem calls these methods automatically.

Extended by

Constructors

Constructor

new Component(): Component

Returns

Component

Properties

entity

entity: Entity

Defined in: Component.ts:22

Back-reference to the owning entity. Set by the engine when the component is added to an entity. Do not set manually.

restorePriority?

static optional restorePriority?: number

Defined in: Component.ts:345

Snapshot restore order. On load, an entity’s components are re-added in ascending priority, so a component whose onAdd() reads a sibling can rely on lower-priority siblings being present and initialized. Undeclared = 100. Engine components reserve 0-99; game and addon components declare a value only when a sibling onAdd() dependency requires it. Equal priorities restore in save-time add order. Subclasses inherit their base class’s priority unless they declare their own.

updatePriority?

static optional updatePriority?: number

Defined in: Component.ts:361

Class-level default for updatePriority: every instance runs at this priority unless its own updatePriority is written. Undeclared = 0. Subclasses inherit their base class’s value unless they declare their own. Declare it on a component whose behavior depends on running after (or before) a sibling, so the entity that adds it does not have to control the add order.

class BoundsClamp extends Component {
  static updatePriority = 10; // after the follow that moves the camera
}

Accessors

context

Get Signature

get context(): EngineContext

Defined in: Component.ts:109

Access the EngineContext from the entity’s scene. Throws if the entity is not in a scene.

Returns

EngineContext

effectiveEnabled

Get Signature

get effectiveEnabled(): boolean

Defined in: Component.ts:56

Whether the component is actually running: enabled, on an active entity, and past onAdd. This is the state onEnable and onDisable track — read it when a method has to behave one way live and another way dormant.

Returns

boolean

enabled

Get Signature

get enabled(): boolean

Defined in: Component.ts:40

Whether this component runs. Disabled components are skipped by ComponentUpdateSystem.

Writing this fires onEnable / onDisable when the effective state changes — enabled && entity.isActive. A component disabled here stays disabled through a setActive(false) / setActive(true) cycle on its entity.

Returns

boolean

Set Signature

set enabled(value): void

Defined in: Component.ts:44

Parameters

value

boolean

Returns

void

scene

Get Signature

get scene(): Scene

Defined in: Component.ts:95

Access the entity’s scene. Throws if the entity is not in a scene. Prefer this over threading through this.entity.scene in component code.

Returns

Scene

updatePriority

Get Signature

get updatePriority(): number

Defined in: Component.ts:77

Where this component runs among its siblings. ComponentUpdateSystem calls update / fixedUpdate on an entity’s components in ascending priority; equal priorities run in add order. Undeclared = 0, so a negative value runs before siblings that keep the default and a positive value runs after them. Writable at any time, before or after add(). Defaults to the class’s static updatePriority.

class Player extends Entity {
  setup() {
    this.add(new Mover());
    this.add(new Brain()).updatePriority = -1; // decides before Mover moves
  }
}

Returns

number

Set Signature

set updatePriority(value): void

Defined in: Component.ts:85

Parameters

value

number

Returns

void

Methods

_applyEnabled()

_applyEnabled(effective): void

Defined in: Component.ts:274

Internal

Force an effective-enabled transition, firing the hook on a flip. Used by Entity for teardown, where enabled and the entity’s activeness both still read true.

Parameters

effective

boolean

Returns

void

_refreshEnabled()

_refreshEnabled(): void

Defined in: Component.ts:263

Internal

Recompute effective enabled-ness from enabled and the entity’s activeness, firing the hook on a flip.

Returns

void

_runCleanups()

_runCleanups(): void

Defined in: Component.ts:249

Internal

Run and clear all registered cleanups. Called by Entity.remove() and Entity._performDestroy() before onRemove/onDestroy.

Returns

void

addCleanup()

protected addCleanup(fn): void

Defined in: Component.ts:239

Parameters

fn

() => void

Returns

void

afterRestore()?

optional afterRestore(data, resolve): void

Defined in: Component.ts:367

Called after onAdd() during save/load restoration. Apply state that depends on onAdd() having run.

Parameters

data

unknown

resolve

SnapshotResolver

Returns

void

fixedUpdate()?

optional fixedUpdate(dt): void

Defined in: Component.ts:333

Called every fixed timestep by the built-in ComponentUpdateSystem.

Parameters

dt

number

Fixed timestep in seconds, scaled by scene and entity timeScale.

Returns

void

listen()

protected listen<T>(entity, token, handler): void

Defined in: Component.ts:216

Subscribe to events on any entity, auto-unsubscribe on removal.

Type Parameters

T

T

Parameters

entity

Entity

token

EventToken<T>

handler

(data) => void

Returns

void

listenScene()

protected listenScene<T>(token, handler): void

Defined in: Component.ts:230

Subscribe to scene-level events, auto-unsubscribe on removal. Handlers fire for bubbled entity events (entity = source) and scene.emit events (entity = undefined).

Type Parameters

T

T

Parameters

token

EventToken<T>

handler

(data, entity?) => void

Returns

void

onAdd()?

optional onAdd(): void

Defined in: Component.ts:296

Called when the component is added to an entity. Validate dependencies here — a service, a sibling component, a render layer — and throw when one is missing. The throw is attributed to this component, recorded in Inspector.getErrors().callbackErrors, and rethrown, so it reaches the caller of entity.add() unchanged.

Returns

void

onDestroy()?

optional onDestroy(): void

Defined in: Component.ts:321

Called when the component is destroyed (entity destroyed or component removed).

Returns

void

onDisable()?

optional onDisable(): void

Defined in: Component.ts:315

Called when the component stops being effectively enabled — enabled went false, the entity (or an ancestor) was deactivated, or the component is being removed or destroyed. Put live resources to sleep here; the component is reused afterwards, so do not free anything onEnable cannot rebuild.

Returns

void

onEnable()?

optional onEnable(): void

Defined in: Component.ts:306

Called when the component becomes effectively enabled — enabled is true and the entity is active. Fires right after onAdd() for a component added to an active entity, and again on every later flip. Bring live resources back online here (unpause a sound, show a display object, re-enable a physics body). Game-state reset does not belong here: the hook sees whatever state the component held while dormant.

Returns

void

onRemove()?

optional onRemove(): void

Defined in: Component.ts:318

Called when the component is removed from an entity.

Returns

void

serialize()?

optional serialize(): unknown

Defined in: Component.ts:364

Return a JSON-serializable snapshot of this component’s state. Used by the save system.

Returns

unknown

service()

protected service<T>(key): T

Defined in: Component.ts:172

Lazy proxy-based service resolution. Can be used at field-declaration time:

readonly input = this.service(InputManagerKey);

The actual resolution is deferred until first property access.

Type Parameters

T

T extends object

Parameters

key

ServiceKey<T>

Returns

T

sibling()

protected sibling<C>(cls): C

Defined in: Component.ts:197

Lazy proxy-based sibling component resolution. Can be used at field-declaration time:

readonly anim = this.sibling(AnimatedSpriteComponent);

The actual resolution is deferred until first property access.

Type Parameters

C

C extends Component

Parameters

cls

ComponentClass<C>

Returns

C

update()?

optional update(dt): void

Defined in: Component.ts:327

Called every frame by the built-in ComponentUpdateSystem.

Parameters

dt

number

Frame delta in seconds, scaled by scene and entity timeScale.

Returns

void

use()

protected use<T>(key): T

Defined in: Component.ts:120

Resolve a service by key, cached after first lookup. Scene-scoped values (registered via scene._registerScoped) take precedence over engine scope. A key declared with scope: "scene" that falls back to engine scope emits a one-shot dev warning — almost always signals a missed beforeEnter hook.

Type Parameters

T

T

Parameters

key

ServiceKey<T>

Returns

T