@obsidize/logger/core/event-emitter.js

A tiny javascript logging library

/**
 * Lightweight event broadcaster.
 *
 * While this class' primary use in the library is for
 * sending log events to registered listeners, it
 * is defined to be generic, and can technically
 * emit any type of value.
 *
 * Feel free to use this for non-logging things since
 * javascript has no built-in observer pattern...
 */
export class EventEmitter {
    constructor() {
        this.mListeners = [];
    }
    get listenerCount() {
        return this.mListeners.length;
    }
    emit(value) {
        for (const listener of this.mListeners)
            listener(value);
        return this;
    }
    hasListener(listener) {
        return this.mListeners.indexOf(listener) >= 0;
    }
    addListener(listener) {
        if (typeof listener === 'function' && !this.hasListener(listener))
            this.mListeners.push(listener);
        return this;
    }
    removeListener(listener) {
        const index = this.mListeners.indexOf(listener);
        if (index >= 0)
            this.mListeners.splice(index, 1);
        return this;
    }
    removeAllListeners() {
        while (this.mListeners.length > 0)
            this.mListeners.pop();
        return this;
    }
}