docs(operators): add documentation for mergeMap

Author: sumitarora

src/app/operators/components/operator-parameters/operator-parameters.component.html

@@ -13,7 +13,7 @@ <h2> Parameters </h2>
       <td> {{parameter.name}} </td>
       <td> {{parameter.type}} </td>
       <td> {{parameter.attribute}} </td>
-      <td> {{parameter.description}} </td>
+      <td [innerHTML]="parameter.description"></td>
     </tr>
   </tbody>
 </table>

src/operator-docs/transformation/mergeMap.ts

@@ -1,6 +1,92 @@
 import { OperatorDoc } from '../operator.model';
 
 export const mergeMap: OperatorDoc = {
-  'name': 'mergeMap',
-  'operatorType': 'transformation'
+  name: 'mergeMap',
+  operatorType: 'transformation',
+  signature: `public mergeMap(project: function(value: T, ?index: number): ObservableInput,
+    resultSelector: function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any, concurrent: number): Observable`,
+  parameters: [
+    {
+      name: 'project',
+      type: 'function(value: T, ?index: number): ObservableInput',
+      attribute: '',
+      description:
+        'A function that, when applied to an item emitted by the source Observable, returns an Observable.'
+    },
+    {
+      name: 'resultSelector',
+      type:
+        'function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any',
+      attribute: 'optional',
+      description: `
+        A function to produce the value on the output Observable based on the values and the indices of the source
+        (outer) emission and the inner Observable emission. The arguments passed to this function are:
+        <ul>
+        <li>outerValue: the value that came from the source</li>
+        <li>innerValue: the value that came from the projected Observable</li>
+        <li>outerIndex: the "index" of the value that came from the source</li>
+        <li>innerIndex: the "index" of the value from the projected Observable</li>
+        </ul>
+      `
+    },
+    {
+      name: 'concurrent',
+      type: 'number',
+      attribute: 'optional default: Number.POSITIVE_INFINITY',
+      description:
+        'Maximum number of input Observables being subscribed to concurrently.'
+    }
+  ],
+  marbleUrl: 'http://reactivex.io/rxjs/img/mergeMap.png',
+  shortDescription: {
+    description:
+      'Projects each source value to an Observable which is merged in the output Observable.',
+    extras: [
+      {
+        type: 'Tip',
+        text:
+          'Maps each value to an Observable, then flattens all of these inner Observables using mergeAll.'
+      }
+    ]
+  },
+  walkthrough: {
+    description: `<p>Returns an Observable that emits items based on applying a function that you
+    supply to each item emitted by the source Observable, where that function
+    returns an Observable, and then merging those resulting Observables and
+    emitting the results of this merger.</p>`
+  },
+  examples: [
+    {
+      name:
+        'Map and flatten each letter to an Observable ticking every 1 second',
+      code: `
+      const letters = Rx.Observable.of('a', 'b', 'c');
+      const result = letters.mergeMap(x =>
+        Rx.Observable.interval(1000).map(i => x+i)
+      );
+      result.subscribe(x => console.log(x));
+      // Results in the following:
+      // a0
+      // b0
+      // c0
+      // a1
+      // b1
+      // c1
+      // continues to list a,b,c with respective ascending integers
+    `,
+      externalLink: {
+        platform: 'JSBin',
+        url: 'http://jsbin.com/hehivasepi/1/embed?js,console'
+      }
+    }
+  ],
+  relatedOperators: [
+    'concatMap',
+    'exhaustMap',
+    'merge',
+    'mergeAll',
+    'mergeMapTo',
+    'mergeScan',
+    'switchMap'
+  ]
 };