Reactive-Extensions/RxJS

# This is RxJS v 4. [Find the latest version here](https://github.com/reactivex/rxjs)
### `Rx.Observable.case(selector, sources, [elseSource|scheduler])`
[Ⓢ](https://github.com/Reactive-Extensions/RxJS/blob/master/src/core/linq/observable/case.js "View in source")
 
Uses selector to determine which source in sources to use.  There is an alias 'switchCase' for browsers <IE9.
 
### Arguments
1. `selector` *(`Function`)*: The function which extracts the value for to test in a case statement.
2. `sources` *(`Object`)*: An object which has keys which correspond to the case statement labels.
3. `[elseSource|scheduler]` *(`Observable` | `Scheduler`)*: The observable sequence that will be run if the sources are not matched. If this is not provided, it defaults to `Rx.Observabe.empty` with the specified scheduler.
 
#### Returns
*(`Observable`)*: An observable sequence which is determined by a case statement.
 
#### Example
```js
var sources = {
    'foo': Rx.Observable.return(42),
    'bar': Rx.Observable.return(56)
};
 
var defaultSource = Rx.Observable.empty();
 
var source = Rx.Observable.case(
    function () {
        return 'foo';
    },
    sources,
    defaultSource);
 
var subscription = source.subscribe(
    function (x) {
        console.log('Next: ' + x);
    },
    function (err) {
        console.log('Error: ' + err);
    },
    function () {
        console.log('Completed');
    });
 
//=> Next: 42
//=> Completed
```
 
### Location
 
File:
- [`/src/core/linq/observable/case.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/src/core/linq/observable/case.js)
 
Dist:
- [`rx.all.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.all.js)
- [`rx.all.compat.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.all.compat.js)
- [`rx.experimental.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.experimental.js)
 
Prerequisites:
- If using `rx.expermental.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.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)
 
NPM Packages:
- [`rx`](https://www.npmjs.org/package/rx)
 
NuGet Packages:
- [`RxJS-Complete`](http://www.nuget.org/packages/RxJS-Complete)
- [`RxJS-Experimental`](http://www.nuget.org/packages/RxJS-Experimental)
 
Unit Tests:
- [`/tests/observable/case.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/tests/observable/case.js)