Reactive-Extensions/RxJS

# This is RxJS v 4. [Find the latest version here](https://github.com/reactivex/rxjs)
### `Rx.Observable.fromEventPattern(addHandler, [removeHandler], [selector])`
[Ⓢ](https://github.com/Reactive-Extensions/RxJS/blob/master/src/core/linq/observable/fromeventpattern.js "View in source")
 
Creates an observable sequence by using the addHandler and removeHandler functions to add and remove the handlers, with an optional selector function to project the event arguments.
 
#### Arguments
1. `addHandler` *(`Function`)*: The DOMElement, NodeList or EventEmitter to attach a listener.
2. `[removeHandler]` *(`Function`)*: The optional function to remove a handler from an emitter.
3. `[selector]` *(`Function`)*: A selector which takes the arguments from the event handler to produce a single item to yield on next.
 
#### Returns
*(`Observable`)*: An observable sequence of events from the specified element and the specified event.
 
#### Example
 
Wrapping an event from [jQuery](http://jquery.com)
 
```js
var input = $('#input');
 
var source = Rx.Observable.fromEventPattern(
  function add (h) {
    input.bind('click', h);
  },
  function remove (h) {
    input.unbind('click', h);
  }
);
 
var subscription = source.subscribe(
  function (x) {
    console.log('Next: Clicked!');
  },
  function (err) {
    console.log('Error: %s', err);
  },
  function () {
    console.log('Completed');
  });
 
input.trigger('click');
 
// => Next: Clicked!
```
 
Wrapping an event from the [Dojo Toolkit](http://dojotoolkit.org)
 
```js
require(['dojo/on', 'dojo/dom', 'rx', 'rx.async', 'rx.binding'], function (on, dom, rx) {
 
  var input = dom.byId('input');
 
  var source = Rx.Observable.fromEventPattern(
    function add (h) {
      return on(input, 'click', h);
    },
    function remove (_, signal) {
      signal.remove();
    }
  );
 
  var subscription = source.subscribe(
    function (x) {
      console.log('Next: Clicked!');
    },
    function (err) {
      console.log('Error: ' + err);
    },
    function () {
      console.log('Completed');
    });
 
  on.emit(input, 'click');
  // => Next: Clicked!
});
```
 
Using in Node.js with using an `EventEmitter`.
 
```js
var EventEmitter = require('events').EventEmitter,
    Rx = require('rx');
 
var e = new EventEmitter();
 
// Wrap EventEmitter
var source = Rx.Observable.fromEventPattern(
  function add (h) {
    e.addListener('data', h);
  },
  function remove (h) {
    e.removeListener('data', h);
  },
  function (foo, bar) {
    return foo + ',' + bar;
  }
);
 
var subscription = source.subscribe(
  function (result) {
    console.log('Next: %s', result);
  },
  function (err) {
    console.log('Error: ' + err);
  },
  function () {
    console.log('Completed');
  });
 
e.emit('data', 'foo', 'bar');
// => Next: foo,bar
```
 
### Location
 
File:
- [/src/core/linq/observable/fromeventpattern.js](https://github.com/Reactive-Extensions/RxJS/blob/master/src/core/linq/observable/fromeventpattern.js)
 
Dist:
- [`rx.async.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.async.js)
- [`rx.async.compat.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.async.compat.js)
- [`rx.lite.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.lite.js)
- [`rx.lite.compat.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.lite.compat.js)
 
Prerequisites:
- If using rx.async.js | rx.async.compat.js
    - [`rx.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.js) | [`rx.compat.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.compat.js)
    - [`rx.binding.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.binding.js)
- [`rx`](https://www.npmjs.org/package/rx).lite.js | rx.lite.compat.js
 
NPM Packages:
- [`rx`](https://www.npmjs.org/package/rx)
 
NuGet Packages:
- [`RxJS-Async`](http://www.nuget.org/packages/RxJS-Async)
- [`RxJS-Lite`](http://www.nuget.org/packages/RxJS-Lite/)
 
Unit Tests:
- [/tests/observable/fromeventpattern.js](https://github.com/Reactive-Extensions/RxJS/blob/master/tests/observable/fromeventpattern.js)