@needle-tools/engine/src/engine/engine_components_internal.ts

Needle Engine is a web-based runtime for 3D apps. It runs on your machine for development with great integrations into editors like Unity or Blender - and can be deployed onto any device! It is flexible, extensible and networking and XR are built-in.

import { type IComponent } from "./engine_types.js";
import { getParam } from "./engine_utils.js";


type ComponentLifecycleEvent = "component-added" | "removing-component";

const debug = getParam("debugcomponentevents");

export class ComponentLifecycleEvents {

    private static eventListeners = new Map<string, ((data: IComponent) => void)[]>();

    static addComponentLifecylceEventListener(evt: ComponentLifecycleEvent | (string & {}), cb: (data: IComponent) => void) {
        if (this.eventListeners.has(evt)) {
            this.eventListeners.set(evt, []);
        }
        let arr = this.eventListeners.get(evt);
        if (!arr) arr = [];
        arr.push(cb);
        this.eventListeners.set(evt, arr);
        if(debug) console.log("Added event listener for " + evt, this.eventListeners)
    }

    static removeComponentLifecylceEventListener(evt: ComponentLifecycleEvent | (string & {}), cb: (data: IComponent) => void) {
        const listeners = this.eventListeners.get(evt);
        if (!listeners) return;
        const index = listeners.indexOf(cb);
        if (index < 0) return;
        listeners.splice(index, 1);
        
    }

    static dispatchComponentLifecycleEvent(evt: ComponentLifecycleEvent, data: IComponent) {
        const listeners = this.eventListeners.get(evt);
        if(debug) console.log("Dispatching event " + evt, listeners)
        if (!listeners) return;
        for (const listener of listeners) {
            listener(data);
        }
    }
}