doc/api/core/operators/includes.md
# This is RxJS v 4. [Find the latest version here](https://github.com/reactivex/rxjs)### `Rx.Observable.prototype.includes(searchElement, [fromIndex])` ###### `Rx.Observable.prototype.contains(searchElement, [fromIndex])` **DEPRECATED** ###[Ⓢ](https://github.com/Reactive-Extensions/RxJS/blob/master/src/core/linq/observable/includes.js "View in source") Determines whether an observable sequence includes a specified element with an optional from index. #### Arguments1. `searchElement` *(`Any`)*: The value to locate in the source sequence.2. `[fromIndex]` *(`Number`)*: The index to start the search. If not specified, defaults to 0. #### Returns*(`Observable`)*: An observable sequence containing a single element determining whether the source sequence includes an element that has the specified value with an optional from index. #### Example```js/* Without an index */var source = Rx.Observable.of(42) .includes(42); var subscription = source.subscribe( function (x) { console.log('Next: %s', x); }, function (err) { console.log('Error: %s', err); }, function () { console.log('Completed'); }); // => Next: true// => Completed /* With an index */var source = Rx.Observable.of(1,2,3) .includes(2, 1); var subscription = source.subscribe( function (x) { console.log('Next: %s', x); }, function (err) { console.log('Error: %s', err); }, function () { console.log('Completed'); }); // => Next: true// => Completed```### Location File:- [`/src/core/linq/observable/includes.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/src/core/linq/observable/includes.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.js)- [`rx.aggregates.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/dist/rx.aggregates.js) Prerequisites:- [`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-All`](http://www.nuget.org/packages/RxJS-All/)- [`RxJS-Aggregates`](http://www.nuget.org/packages/RxJS-Aggregates/) Unit Tests:- [`/tests/observable/includes.js`](https://github.com/Reactive-Extensions/RxJS/blob/master/tests/observable/includes.js)