Merge pull request #184 from sumitarora/docs-withLatestFrom

docs(operators): add documentation for withLatestFrom

Author: ashwin-sureshkumar

src/operator-docs/combination/withLatestFrom.ts

@@ -1,6 +1,46 @@
 import { OperatorDoc } from '../operator.model';
 
 export const withLatestFrom: OperatorDoc = {
-  'name': 'withLatestFrom',
-  'operatorType': 'combination'
+  name: 'withLatestFrom',
+  operatorType: 'combination',
+  signature:
+    'public withLatestFrom(other: ObservableInput, project: Function): Observable',
+  marbleUrl: 'http://reactivex.io/rxjs/img/withLatestFrom.png',
+  shortDescription: {
+    description: `Combines the source Observable with other Observables to create an Observable whose values are
+      calculated from the latest values of each, only when the source emits.`,
+    extras: [
+      {
+        type: 'Tip',
+        text: `Whenever the source Observable emits a value, it computes a formula using that
+      value plus the latest values from other input Observables, then emits the output of that formula.`
+      }
+    ]
+  },
+  walkthrough: {
+    description: `
+        <p><span class="markdown-code">withLatestFrom</span> combines each value from the source Observable (the instance) with the latest
+        values from the other input Observables only when the source emits a value, optionally using
+        a project function to determine the value to be emitted on the output Observable. All input
+        Observables must emit at least one value before the output Observable will emit a value.
+        </p>
+      `
+  },
+  examples: [
+    {
+      name:
+        'For each click event, tick every second from 0 to 3, with no concurrency',
+      code: `
+        const clicks = Rx.Observable.fromEvent(document, 'click');
+        const higherOrder = clicks.map(ev => Rx.Observable.interval(1000).take(4));
+        const firstOrder = higherOrder.concatAll();
+        firstOrder.subscribe(x => console.log(x));
+      `,
+      externalLink: {
+        platform: 'JSBin',
+        url: 'http://jsbin.com/wojoqenitu/1/embed?js,console,output'
+      }
+    }
+  ],
+  relatedOperators: ['combineLatest']
 };