mittt

Mittt

Tiny functional event emitter / pubsub.
Forked from https://github.com/developit/mitt
New project created from TSDX CLI.

• Microscopic: weighs ~200 bytes gzipped size.
• Functional: methods don't rely on this

Mittt was made for the browser, but works in any JavaScript runtime. It has no dependencies and supports IE9+.

Table of Contents

• Install
• Usage

Install

This project uses node and npm. Go check them out if you don't have them locally installed.

$ npm install mittt
# or
# yarn add mittt

Then with a module bundler like rollup or webpack, use as you would anything else:

// using ES6 modules
import mittt from 'mittt'

// using CommonJS modules
var mittt = require('mittt')

The ESM build is also available on unpkg:

<script type="module" src="https://unpkg.com/mittt/dist/mittt.esm.js"></script>

Usage

import mittt from 'mittt'

const emitter = mittt()

function onEvent(eventType, payload) {
  console.log(eventType, payload)
}

// Listen to an event
emitter.on('foo', onEvent)

// Fire an event
emitter.emit('foo')

// Fire an event with payload
const payload = { a: 'b' }
emitter.emit('bar', payload)

// Working with handler references:
emitter.on('foo', onEvent) // listen
emitter.off('foo', onEvent) // unlisten

// Initiate emitter with on event setup
const emitter = mittt({
  foo: [
    (eventType, payload) => {
      console.log(eventType, payload) // foo, undefined
    },
    (eventType, payload) => {
      console.log(eventType, payload) // foo, undefined
    },
  ],
})

emitter.emit('foo') // all handlers for foo are invoked

TypeScript

import mittt, { Emitter, EventHandler } from 'mittt'
const emitter: Emitter = mittt()

let foo: EventHandler = (eventType, payload) => {}

emitter.on('foo', foo)