micromitter

minimal and performant event emitter / emitter with custom events and payload

API

Table of Contents

• constructor
• on
• off
• once
• emit

constructor

Creates an instance of MicroMitter.

Parameters

• target any the event target

on

adds an event handler to an event type

Parameters

• type string
• handler function

Examples

emitter.on('type', (e)=>{
console.log(e);
});

Returns MicroMitter self

off

removes either a specific handler or all handlers related to an event type

Parameters

• type string
• handler function

Returns MicroMitter self

once

adds an event handler to an event type and immediately removes it after first event call

Parameters

• type string
• handler function

Examples

emitter.onc('type', (e)=>{
console.log('only once');
});

Returns MicroMitter self

emit

triggers an event for a specific type with an optional data object

Parameters

• type string
• data any (optional, default {})

Examples

emitter.off('type', handler);

Returns MicroMitter self

Usage

import Emitter from 'micromitter';
const emitter = new Emitter();
emitter.on('test', (e)=>{
  console.log(e.type === 'test');
  console.log(e.foo === 'bar');
});
emitter.emit('test', {foo:'bar'});
emitter.off('test');
let counter = 0;
emitter.once('oneTime', (e)=>{
  counter += 1;
});
emitter.emit('oneTime', {foo:'bar'});
emitter.emit('oneTime', {foo:'bar'});
emitter.emit('oneTime', {foo:'bar'});
emitter.emit('oneTime', {foo:'bar'});
console.log(counter); // 1

chaining

emitter
  .on('type', handler)
  .emit('type', {foo:'bar'})
  .off('type', handler);

use global instance

import {emitter} from 'micromitter';
emitter.on('test', (e)=>{
  console.log(e.type === 'test');
  console.log(e.foo === 'bar');
});
emitter.emit('test', {foo:'bar'});

use decorator

import { micromitter } from 'micromitter';
//v1: use es7 decorators
@micromitter
class Tester {
    onTest(e){
        console.log(e.type === 'test');
        console.log(e.foo === 'bar');
    }
}
//v2 use the decorator as a function
micromitter(Tester);
const tt = new Tester();
tt.on('test', tt.onTest);
tt.emit('test', {foo:'bar'});