docs(example): provide __DEV__ replacement (#369)

Author: francoischalifour

examples/js/index.html

@@ -13,6 +13,7 @@
       <div id="autocomplete"></div>
     </div>
 
+    <script src="index.ts"></script>
     <script src="app.ts"></script>
   </body>
 </html>

examples/js/index.ts

@@ -0,0 +1,5 @@
+// Parcel picks the `source` field of the monorepo packages and thus doesn't
+// apply the Babel config to replace our `__DEV__` global expression.
+// We therefore need to manually override it in the example app.
+// See https://twitter.com/devongovett/status/1134231234605830144
+(global as any).__DEV__ = process.env.NODE_ENV !== 'production';