docs(operators): examples for groupBy operator (#2219)

* docs(operators): examples for groupBy operator * style(lint): fix trailing whitespace
ReactiveX · Apr 3, 2017 · c60c387 · c60c387
1 parent 840def0
commit c60c387
Showing 1 changed file with 46 additions and 0 deletions.
diff --git a/src/operator/groupBy.ts b/src/operator/groupBy.ts
@@ -20,6 +20,52 @@ export function groupBy<T, K, R>(this: Observable<T>, keySelector: (value: T) =>
  *
  * <img src="./img/groupBy.png" width="100%">
  *
+ * @example <caption>Group objects by id and return as array</caption>
+ * Observable.of<Obj>({id: 1, name: 'aze1'},
+ *                    {id: 2, name: 'sf2'},
+ *                    {id: 2, name: 'dg2'},
+ *                    {id: 1, name: 'erg1'},
+ *                    {id: 1, name: 'df1'},
+ *                    {id: 2, name: 'sfqfb2'},
+ *                    {id: 3, name: 'qfs3'},
+ *                    {id: 2, name: 'qsgqsfg2'}
+ *     )
+ *     .groupBy(p => p.id)
+ *     .flatMap( (group$) => group$.reduce((acc, cur) => [...acc, cur], []))
+ *     .subscribe(p => console.log(p));
+ *
+ * // displays:
+ * // [ { id: 1, name: 'aze1' },
+ * //   { id: 1, name: 'erg1' },
+ * //   { id: 1, name: 'df1' } ]
+ * //
+ * // [ { id: 2, name: 'sf2' },
+ * //   { id: 2, name: 'dg2' },
+ * //   { id: 2, name: 'sfqfb2' },
+ * //   { id: 2, name: 'qsgqsfg2' } ]
+ * //
+ * // [ { id: 3, name: 'qfs3' } ]
+ *
+ * @example <caption>Pivot data on the id field</caption>
+ * Observable.of<Obj>({id: 1, name: 'aze1'},
+ *                    {id: 2, name: 'sf2'},
+ *                    {id: 2, name: 'dg2'},
+ *                    {id: 1, name: 'erg1'},
+ *                    {id: 1, name: 'df1'},
+ *                    {id: 2, name: 'sfqfb2'},
+ *                    {id: 3, name: 'qfs1'},
+ *                    {id: 2, name: 'qsgqsfg2'}
+ *                   )
+ *     .groupBy(p => p.id, p => p.anme)
+ *     .flatMap( (group$) => group$.reduce((acc, cur) => [...acc, cur], ["" + group$.key]))
+ *     .map(arr => ({'id': parseInt(arr[0]), 'values': arr.slice(1)}))
+ *     .subscribe(p => console.log(p));
+ *
+ * // displays:
+ * // { id: 1, values: [ 'aze1', 'erg1', 'df1' ] }
+ * // { id: 2, values: [ 'sf2', 'dg2', 'sfqfb2', 'qsgqsfg2' ] }
+ * // { id: 3, values: [ 'qfs1' ] }
+ *
  * @param {function(value: T): K} keySelector A function that extracts the key
  * for each item.
  * @param {function(value: T): R} [elementSelector] A function that extracts the