Add example for configuration object usage (#53)

Author: Eskibear

examples/configObject.mjs

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+import * as dotenv from "dotenv";
+dotenv.config()
+
+/**
+ * This example demonstrates how to construct a configuration object from settings loaded from Azure App Configuration.
+ * If you are using configuration object instead of Map-styled settings, it would minimize the code changes required to use Azure App Configuration in your application.
+ *
+ * When you import configuration into Azure App Configuration from a local .json file, the keys are automatically flattened with a separator if specified.
+ * E.g. if you import the following .json file, specifying the separator as ".":
+ * {
+ *   "app": {
+ *     "settings": {
+ *       "message": "Hello, Azure!"
+ *     }
+ *   }
+ * }
+ *
+ * In the configuration explorer, the key-values will be:
+ *  - Key: "app.settings.message", Value: "Hello, Azure!"
+ *
+ * With the API `constructConfigurationObject`, you can construct a configuration object with the same shape as the original .json file.
+ * The separator is used to split the keys and construct the object.
+ * The constructed object will be: { app: { settings: { message: "Hello, Azure!" } } }
+ *
+ * Below environment variables are required for this example:
+ * - APPCONFIG_CONNECTION_STRING
+ */
+
+import { load } from "@azure/app-configuration-provider";
+const connectionString = process.env.APPCONFIG_CONNECTION_STRING;
+const settings = await load(connectionString, {
+    selectors: [{
+        keyFilter: "app.settings.*"
+    }]
+});
+
+const config = settings.constructConfigurationObject({
+    separator: "."
+});
+
+console.log("Constructed object 'config': ", config);
+console.log(`Message from Azure App Configuration: ${config.app.settings.message}`);