5.5 KiB
Mitt
Tiny 200b functional event emitter / pubsub.
- 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+.
Table of Contents
Install
This project uses node and npm. Go check them out if you don't have them locally installed.
$ npm install --save mitt
Then with a module bundler like rollup or webpack, use as you would anything else:
// using ES6 modules
import mitt from 'mitt'
// using CommonJS modules
var mitt = require('mitt')
The UMD build is also available on unpkg:
<script src="https://unpkg.com/mitt/dist/mitt.umd.js"></script>
You can find the library on window.mitt.
Usage
import mitt from 'mitt'
const 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' })
// clearing all events
emitter.all.clear()
// working with handler references:
function onFoo() {}
emitter.on('foo', onFoo) // listen
emitter.off('foo', onFoo) // unlisten
Typescript
import mitt from 'mitt';
const emitter: mitt.Emitter = mitt();
Examples & Demos
Preact + Mitt Codepen Demo
API
Table of Contents
mitt
Mitt: Tiny (~200b) functional event emitter / pubsub.
Returns Mitt
all
A Map of event names to registered handler functions.
on
Register an event handler for the given type.
Parameters
type(string | symbol) Type of event to listen for, or"*"for all eventshandlerFunction Function to call in response to given event
off
Remove an event handler for the given type.
Parameters
type(string | symbol) Type of event to unregisterhandlerfrom, or"*"handlerFunction Handler function to remove
emit
Invoke all handlers for the given type.
If present, "*" handlers are invoked after type-matched handlers.
Note: Manually firing "*" handlers is not supported.
Parameters
type(string | symbol) The event type to invokeevtAny? Any value (object is recommended and powerful), passed to each handler
Contribute
First off, thanks for taking the time to contribute! Now, take a moment to be sure your contributions make sense to everyone else.
Reporting Issues
Found a problem? Want a new feature? First of all see if your issue or idea has already been reported. If don't, just open a new clear and descriptive issue.
Submitting pull requests
Pull requests are the greatest contributions, so be sure they are focused in scope, and do avoid unrelated commits.
- Fork it!
- Clone your fork:
git clone https://github.com/<your-username>/mitt - Navigate to the newly cloned directory:
cd mitt - Create a new branch for the new feature:
git checkout -b my-new-feature - Install the tools necessary for development:
npm install - Make your changes.
- Commit your changes:
git commit -am 'Add some feature' - Push to the branch:
git push origin my-new-feature - Submit a pull request with full remarks documenting your changes.