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.