aweary / mitt

Tiny 200b functional event emitter / pubsub.

Mitt: tiny 200b functional event emitter / pubsub.

Why Mitt?

• Microscopic: weighs less than 200 bytes gzipped
• Useful: a wildcard "*" event type listens to all events
• Familiar: same names & ideas as Node's EventEmitter
• Functional: methods don't rely on this
• Great Name: somehow mitt wasn't taken

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

Examples & Demos

Preact + Mitt Codepen Demo

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Usage

After installing via npm install --save mitt:

import mitt from 'mitt'

let emitter = mitt()

// listen to an event
emitter.on('foo', e => console.log('foo', e) )

// listen to all events
emitter.on('*', (type, e) => console.log(type, e) )

// fire an event
emitter.emit('foo', { a: 'b' })

// working with handler references:
function onFoo() {}
emitter.on('foo', onFoo)   // listen
emitter.off('foo', onFoo)  // unlisten

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API

mitt

Mitt: Tiny (~200b) functional event emitter / pubsub.

Returns Mitt

on

Register an event handler for the given type.

Parameters

• type String Type of event to listen for, or "*" for all events
• handler Function Function to call in response to the given event

off

Remove an event handler for the given type.

Parameters

• type String Type of event to unregister handler from, or "*"
• handler Function Handler function to remove

emit

Invoke all handlers for the given type. If present, "*" handlers are invoked prior to type-matched handlers.

Parameters

• type String The event type to invoke
• event [Any] An event object, passed to each handler