Normally Palatable Mango

    TypeScript icon, indicating that this package has built-in type declarations

    3.0.1 • Public • Published

    npm build status gzip size


    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


    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=""></script>

    You can find the library on window.mitt.


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


    Set "strict": true in your tsconfig.json to get improved type inference for mitt instance methods.

    import mitt from 'mitt';
    type Events = {
      foo: string;
      bar?: number;
    const emitter = mitt<Events>(); // inferred as Emitter<Events>
    emitter.on('foo', (e) => {}); // 'e' has inferred type 'string'
    emitter.emit('foo', 42); // Error: Argument of type 'number' is not assignable to parameter of type 'string'. (2345)

    Alternatively, you can use the provided Emitter type:

    import mitt, { Emitter } from 'mitt';
    type Events = {
      foo: string;
      bar?: number;
    const emitter: Emitter<Events> = mitt<Events>();

    Examples & Demos

    Preact + Mitt Codepen Demo
    preact + mitt preview


    Table of Contents


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

    Returns Mitt


    A Map of event names to registered handler functions.


    Register an event handler for the given type.


    • type (string | symbol) Type of event to listen for, or '*' for all events
    • handler Function Function to call in response to given event
    • keyOfHandler string?


    Remove an event handler for the given type. If handler is omitted, all handlers of the given type are removed.


    • type (string | symbol) Type of event to unregister handler from ('*' to remove a wildcard handler)
    • handler Function? Handler function to remove
    • keyOfHandler string?


    Invoke all handlers for the given type. If present, '*' handlers are invoked after type-matched handlers.

    Note: Manually firing '*' handlers is not supported.


    • type (string | symbol) The event type to invoke
    • evt Any? Any value (object is recommended and powerful), passed to each handler


    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<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.


    MIT License © Jason Miller


    npm i @wingnpm/mitt

    DownloadsWeekly Downloads






    Unpacked Size

    34.2 kB

    Total Files


    Last publish


    • wingnpm