react-form-with-constraints/dist/EventEmitter.js

Simple form validation for React

import { assert } from './assert';
export class EventEmitter {
    constructor() {
        this.listeners = new Map();
    }
    emitSync(eventName, ...args) {
        const listeners = this.getListeners(eventName);
        const ret = new Array();
        listeners.forEach(listener => ret.push(listener(...args)));
        return ret;
    }
    async emitAsync(eventName, ...args) {
        const listeners = this.getListeners(eventName);
        const ret = new Array();
        for (let i = 0; i < listeners.length; i++) {
            ret.push(await listeners[i](...args));
        }
        return ret;
    }
    getListeners(eventName) {
        const listeners = this.listeners.get(eventName);
        if (listeners !== undefined) {
            assert(listeners.length > 0, `No listener for event '${eventName}'`);
            return listeners;
        }
        return [];
    }
    addListener(eventName, listener) {
        if (!this.listeners.has(eventName))
            this.listeners.set(eventName, []);
        const listeners = this.listeners.get(eventName);
        assert(!listeners.includes(listener), `Listener already added for event '${eventName}'`);
        listeners.push(listener);
    }
    removeListener(eventName, listener) {
        const listeners = this.listeners.get(eventName);
        assert(listeners !== undefined, `Unknown event '${eventName}'`);
        const index = listeners.lastIndexOf(listener);
        assert(index > -1, `Listener not found for event '${eventName}'`);
        listeners.splice(index, 1);
        if (listeners.length === 0)
            this.listeners.delete(eventName);
    }
}