Added create-subscription example

examples/update-on-async-rendering/adding-event-listeners-create-subscription.js

@@ -0,0 +1,33 @@
+import {createSubscription} from 'create-subscription';
+
+const Subscription = createSubscription({
+  getCurrentValue(source) {
+    // Return the current value of the subscription (source).
+    // highlight-next-line
+    return source.value;
+  },
+
+  subscribe(source, callback) {
+    function handleSubscriptionChange() {
+      callback(dataSource.value);
+    }
+
+    // Subscribe (e.g. add an event listener) to the subscription (source).
+    // Call callback(newValue) whenever a subscription changes.
+    // highlight-next-line
+    source.subscribe(handleSubscriptionChange);
+
+    // Return an unsubscribe method.
+    // highlight-range{1-3}
+    return function unsubscribe() {
+      source.unsubscribe(handleSubscriptionChange);
+    };
+  },
+});
+
+// Rather than passing the subscribable source to our ExampleComponent,
+// We could just pass the subscribed value directly:
+// highlight-range{1-3}
+<Subscription source={dataSource}>
+  {value => <ExampleComponent subscribedValue={value} />}
+</Subscription>;