docs(operators): add documentation for windowWhen

src/operator-docs/transformation/windowWhen.ts

@@ -1,6 +1,87 @@
 import { OperatorDoc } from '../operator.model';
 
 export const windowWhen: OperatorDoc = {
-  'name': 'windowWhen',
-  'operatorType': 'transformation'
+  name: 'windowWhen',
+  operatorType: 'transformation',
+  signature: `public windowWhen(closingSelector: function(): Observable): Observable`,
+  parameters: [
+    {
+      name: 'closingSelector',
+      type: 'function(): Observable',
+      attribute: '',
+      description: `
+        A function that takes no arguments and returns an Observable that signals
+        (on either 'next' or 'complete') when to close the previous window and start a new one.`
+    }
+  ],
+  marbleUrl: 'http://reactivex.io/rxjs/img/windowWhen.png',
+  shortDescription: {
+    description: `
+      Branch out the source Observable values as a nested Observable using a factory function of
+      closing Observables to determine when to start a new window.`,
+    extras: [
+      {
+        type: 'Tip',
+        text: `
+          It's like <a href="#/operators/bufferWhen" class="markdown-code">bufferWhen</a>,
+          but emits a nested Observable instead of an array.
+        `
+      }
+    ]
+  },
+  walkthrough: {
+    description: `
+      Returns an Observable that emits windows of items it collects from the source Observable. The output Observable
+      emits connected, non-overlapping windows. It emits the current window and opens a new one whenever the Observable
+      produced by the specified <span class="markdown-code">closingSelector</span> function emits an item. The first
+      window is opened immediately when subscribing to the output Observable.`
+  },
+  examples: [
+    {
+      name:
+        'Emit only the first two clicks events in every window of [1-5] random seconds',
+      code: `
+            import { fromEvent } from 'rxjs/observable/fromEvent';
+            import { interval } from 'rxjs/observable/interval';
+            import { mergeAll, tap, windowWhen } from 'rxjs/operators';
+
+            const clicks = fromEvent(document, 'click');
+            const result = clicks.pipe(
+              windowWhen(() => interval(3000)),
+              tap(() => console.log('Window Initated!'))
+            );
+            result.pipe(mergeAll()).subscribe(x => console.log(x));
+
+            /*
+              Example console output
+              'Window Initated!'
+              'Window Initated!'
+              'Window Initated!'
+              'Window Initated!'   //clicked on document
+              [object MouseEvent] {
+                altKey: false,
+                AT_TARGET: 2,
+                bubbles: true,
+                BUBBLING_PHASE: 3,
+                button: 0,
+                buttons: 0,
+                cancelable: true,
+                cancelBubble: false,
+                .... //Entire object properties
+                }
+            */
+      `,
+      externalLink: {
+        platform: 'JSBin',
+        url: 'http://jsbin.com/zegowub/embed?js,console,output'
+      }
+    }
+  ],
+  relatedOperators: [
+    'window',
+    'windowCount',
+    'windowTime',
+    'windowToggle',
+    'bufferWhen'
+  ]
 };