@prismadev/webmarine2d/dist/core/observer/Observable.js

Core utils for 2D verson of game engine Webmarine

import { ExistsError } from "../errors/ExistsError";
import { NotFoundError } from "../errors/NotFoundError";
/** Observable class */
export class Observable {
    /** Make observable */
    constructor() {
        this.listeners = {};
    }
    /** Register observer */
    on(event, callback) {
        if (!this.listeners[event])
            this.listeners[event] = [];
        if (this.listeners[event].find((i) => i.callback === callback))
            throw new ExistsError();
        this.listeners[event].push({ callback, once: false });
        return this.listeners[event].length - 1;
    }
    /** Register observer for one-time call */
    once(event, callback) {
        if (!this.listeners[event])
            this.listeners[event] = [];
        if (this.listeners[event].find((i) => i.callback === callback))
            throw new ExistsError();
        this.listeners[event].push({ callback, once: true });
        return this.listeners[event].length - 1;
    }
    /** Unregister observer */
    off(event, id) {
        if (!this.listeners[event][id])
            throw new NotFoundError();
        this.listeners[event] = this.listeners[event].filter((_, i) => i !== id);
    }
    /** Emit event */
    emit(event) {
        if (!this.listeners[event] || this.listeners[event].length < 1)
            return;
        for (let i = 0; i < this.listeners[event].length; i++) {
            this.listeners[event][i].callback();
            if (this.listeners[event][i].once) {
                this.off(event, i);
            }
        }
    }
    /** Clear observers of event */
    clear(event) {
        if (event)
            this.listeners[event] = [];
        else
            this.listeners = {};
    }
}
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