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https://github.com/chrisdavies/eev

A tiny, fast, zero-dependency event emitter
https://github.com/chrisdavies/eev

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A tiny, fast, zero-dependency event emitter

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# Eev



A tiny, [fast](https://jsperf.com/jsevents/31), zero-dependency event emitter for JavaScript.



- Less than 500 bytes minified + zipped

- Fast... see [jsperf](http://jsperf.com/jsevents/28)

- Zero dependencies

- Simple



[![Build Status](https://travis-ci.org/chrisdavies/eev.svg?branch=master)](https://travis-ci.org/chrisdavies/eev)



## Usage



Create an Eev instance.



```javascript

  var e = new Eev();

```



Then, add handlers as you see fit.



```javascript

  e.on('some-event', function (data) {

    alert('got ' + data);

  });



  e.on('some-event', function (data) {

    console.log('got ' + data);

  });

```



Remove handlers using `off`.



```javascript

  function myHandler (data) { console.log(data); }



  e.on('some-event', myHandler);

  e.off('some-event', myHandler);

```



Trigger events using `emit`.



```javascript

  // The second parameter here is the data you wish to

  // pass to the event handlers

  e.emit('some-event', { foo: 'Bar' });

```



If you want a handler to only run once, you can do this:



```javascript

  e.on('some-event', function foo () {

    e.off('some-event', foo);



    // Do stuff

  });

```



You can register for multiple events at once like this:



```javascript

  function myHandler (data) { console.log(data); }



  e.on('event1 event2 etc', myHandler);

  e.off('event1 event2 etc', myHandler);

```



Stopping propagation isn't build into Eev. If enough people ask for it, I'll bake it in. Meanwile, you can work around this limitation by doing something like this:



```js



  ;(function () {

    var superOn = Eev.prototype.on;



    Eev.prototype.on = function (names, fn) {

      superOn.call(this, names, function (data) {

        if (!data.isCanceled) {

          return fn(data);

        }

      });

    };



  }());



```



With the above patch in place, you can do something like this in your event handlers:



```js

e.on('some-event', function foo (data) {

  data.isCanceled = true; // Now, no downstream handlers should be invoked

})

```



## Installation



Just download eev.min.js, or use bower:



    bower install eev



Or use npm: https://www.npmjs.com/package/eev



    npm install --save eev



## License MIT



Copyright (c) 2015 Chris Davies



Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:



The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.



THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.