mitt

Mitt 2 is out of preview!

• It's written in TypeScript and ships type definitions (#107, thanks again @jackfranklin!)

• Event handlers are now stored in a Map instead of an Object.

  Upgrading: If you aren't passing an object to mitt({}), version 2 is backwards-compatible.
  If you were, turn your object into a map:

  -const handlers = {
  -  foo: [() => alert(1)]
  -};
  +const handlers = new Map();
  +handlers.set('foo', [() => alert(1)]);
  
  const events = mitt(handlers);

• The event handler Map is now exposed as .all: (#105, thanks @jaylinski!)

  const events = mitt();
  events.on('foo', () => alert(1));
  events.on('bar', () => alert(2));
  
  // access handlers directly if needed:
  events.all.get('foo') // [() => alert(1)]
  
  // remove all event handlers:
  events.all.clear();

This patch update for the 2.0 prerelease fixes missing type exports (#101).
It also reduces size and improves performance (#100).

Possible Breaking Change: mitt() previously accepted an optional Object "event map" argument. In 2.0.0, events are stored in an actual JavaScript Map rather than as properties on a plain object:

import mitt from 'mitt';
- const map = {};
+ const map = new Map();

const events = mitt(map);
const foo = () => {};
events.on('foo', foo);

- map.foo // [foo];
+ map.get('foo') // [foo];

Now the good news: if you weren't using this argument, mitt@2 isn't a breaking change for you.

Also, Mitt is now written in TypeScript! Huge thanks to @jackfranklin for doing all the work including setting up a much nicer build toolchain.

It's Mitt's first release since 2017! That's the thing about a 200 byte library - there's not a lot of code here to necessitate constant updates. Take it as a sign of stability.

This release is primarily an improvement to the TypeScript definition we ship with Mitt:

• You can now invoke mitt() with or without new in TypeScript (#60/#67 - thanks @davidkpiano)
• .on('*', handler) now has types that pass the correct (event, data) arguments (#76, thanks @zbuttram)
• The optional all parameter, which lets you pass your own mapping of handler Arrays to Mitt, now has correct types (#73, thanks @jesperzach)

• Fix handler removal (.off()) during emit (#65, thanks @sqal & @farskid)
• Fix emit and EventHandler type annotations (#47, thanks @rvikmanis)
• more precise type annotation for WildCardEventHandler (#58, thanks @tungv)

• Point jsnext:main entry to the ES Modules build instead of src, since src contains Flowtype annotations and a lot of comments.

• Avoid unnecessarily creating listener arrays in off() if they don't exist (saves 4b)

• Refactor courtesy of @tunnckoCore
• Event types have been corrected to be case-sensitive, as they are in Node's EventEmitter.

• Fixes React Native complaining about a Babel configuration (#24, thanks @skellock!)