tom-select/src/contrib/microevent.ts

Tom Select is a versatile and dynamic <select> UI control. Forked from Selectize.js to provide a framework agnostic autocomplete widget with native-feeling keyboard navigation, it's useful for tagging, contact lists, country selectors, etc.

/**
 * MicroEvent - to make any js object an event emitter
 *
 * - pure javascript - server compatible, browser compatible
 * - dont rely on the browser doms
 * - super simple - you get it immediatly, no mistery, no magic involved
 *
 * @author Jerome Etienne (https://github.com/jeromeetienne)
 */

type TCallback = (...args:any) => any;

/**
 * Execute callback for each event in space separated list of event names
 *
 */
function forEvents(events:string,callback:(event:string)=>any){
	events.split(/\s+/).forEach((event) =>{
		callback(event);
	});
}

export default class MicroEvent{

	public _events: {[key:string]:TCallback[]};

	constructor(){
		this._events = {};
	}

	on(events:string, fct:TCallback){
		forEvents(events,(event) => {
			const event_array = this._events[event] || [];
			event_array.push(fct);
			this._events[event] = event_array;
		});
	}

	off(events:string, fct:TCallback){
		var n = arguments.length;
		if( n === 0 ){
			this._events = {};
			return;
		}

		forEvents(events,(event) => {

			if (n === 1){
				delete this._events[event];
				return
			}

			const event_array = this._events[event];
			if( event_array === undefined ) return;

			event_array.splice(event_array.indexOf(fct), 1);
			this._events[event] = event_array;
		});
	}

	trigger(events:string, ...args:any){
		var self = this;

		forEvents(events,(event) => {
			const event_array = self._events[event];
			if( event_array === undefined ) return;
			event_array.forEach(fct => {
				fct.apply(self, args );
			});

		});
	}
};