Better type classes that extends EventEmitter.

Hi, I think that you should better type the classes that extend EventEmitter, using Generics to list and strictly type the events available, instead of just having string | symbol for the name and fn: (...args: Array<any>) => void for the function.

There are a lot of libraries that provide classes with typed events and the one you are using, eventemitter3 can also do it if you update the version you use.

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This is an example of what we have to do without modifying the PIXI to get the proper types :

export type EventList = Record<string, any[]>;

export namespace EventEmitter {
	export type Emit<EventTypes extends EventList> = <K extends keyof EventTypes & string>(event: K, ...args: EventTypes[K]) => boolean;
	export type On<EventTypes extends EventList, This> = <K extends keyof EventTypes & string>(event: K, fn: (...params: EventTypes[K]) => void, context?: any) => This;
	export type Once<EventTypes extends EventList, This> = <K extends keyof EventTypes & string>(event: K, fn: (...params: EventTypes[K]) => void, context?: any) => This;
}

export interface Sprite {
	emit: EventEmitter.Emit<SpriteEvents>;
	on: EventEmitter.On<SpriteEvents, this>;
	once: EventEmitter.Once<SpriteEvents, this>;
}

export type SpriteEvents = {
	added: [container: PIXI.Container];
	click: [event: PIXI.InteractionEvent];
	mousedown: [event: PIXI.InteractionEvent];
	mousemove: [event: PIXI.InteractionEvent];
	mouseout: [event: PIXI.InteractionEvent];
	mouseover: [event: PIXI.InteractionEvent];
	mouseup: [event: PIXI.InteractionEvent];
	mouseupoutside: [event: PIXI.InteractionEvent];
	pointercancel: [event: PIXI.InteractionEvent];
	pointerdown: [event: PIXI.InteractionEvent];
	pointermove: [event: PIXI.InteractionEvent];
	pointerout: [event: PIXI.InteractionEvent];
	pointerover: [event: PIXI.InteractionEvent];
	pointertap: [event: PIXI.InteractionEvent];
	pointerup: [event: PIXI.InteractionEvent];
	pointerupoutside: [event: PIXI.InteractionEvent];
	removed: [container: PIXI.Container];
	removedFrom: [child: PIXI.DisplayObject, container: PIXI.Container, index: number];
	rightclick: [event: PIXI.InteractionEvent];
	rightdown: [event: PIXI.InteractionEvent];
	rightup: [event: PIXI.InteractionEvent];
	rightupoutside: [event: PIXI.InteractionEvent];
	tap: [event: PIXI.InteractionEvent];
	touchcancel: [event: PIXI.InteractionEvent];
	touchend: [event: PIXI.InteractionEvent];
	touchendoutside: [event: PIXI.InteractionEvent];
	touchmove: [event: PIXI.InteractionEvent];
	touchstart: [event: PIXI.InteractionEvent];
};

[bigtimebuddy]

Awesome suggestion. We should incorporate this approach for better typings for events.

[fluffy-heinzelman]

Very good work so far, would love to see this merged!