What is it?

This package implements an event system with minimal dispatch overhead. Instead of recording handlers bound to an event in dynamic data structures, this library binds the handlers to autogenerated code. This enables the VM to inline the handler invocation and generate code that is just as fast as invoking the handlers directly.

In a (completely unscientific) benchmark, this library performs bettern than NodeJS events in terms of event dispatch calls per second by about two orders of magnitude.

How to use it?

Installation

You can install the library into your project via npm

npm install microevent.ts

The library is written in Typescript and will work in any environment that supports ES5. No external typings are required for using this library with Typescript (version >= 2).

Importing

ES5 / CommonJS

var Event = require('microevent.ts').Event;

ES6

import {Event} from 'microevent.ts';

Typescript

import {Event, EventInterface} from 'microevent.ts';

The EventInterface covers only the client side of an event, that is adding and removing handlers.

API

Creating

ES5/ES6

const event = new Event();

Typescript

const event = new Event<PayloadT>();

Create a new event that will dispatch a payload of type PayloadT.

Dispatching

event.dispatch(payload);

This will call all handlers in the order they were registered, passing payload as first argument.

IMPORTANT dispatch is a property that refers to dynamically generated code. DO NOT KEEP ANY REFERENCES to dispatch as adding and removing handlers will invalidate them.

Registering handlers

event.addHandler(handler, context);

context is an optional parameter that will be passed to the handler on each invocation.

Removing handlers

event.removeHandler(handler, context);

Both handler and context must be identical to the values used when registering the handler in the first place.

Checking for handlers

event.isHandlerAttached(handler, context)

This will check whether a handler was attached in a given context.

event.hasHandlers

true if the event has any handlers attached, false otherwise.

License

Feel free to use this library under the conditions of the MIT license.