chore: [js] Document IAS token and destination helper functions

Author: davidkna-sap

docs-js/features/connectivity/destination.mdx

@@ -275,6 +275,9 @@ Note, that if your `serviceBindingTransformFn()` function does not provide a nam
 
 More advanced examples with service token fetching can be found in [service-binding-to-destination.ts](https://github.com/SAP/cloud-sdk-js/blob/main/packages/connectivity/src/scp-cf/destination/service-binding-to-destination.ts).
 
+For the `identity` service type, the SAP Cloud SDK also provides the standalone convenience functions `getIasToken()` and `getIasDestination()`, which can also work with bare `ServiceCredentials` outside of a `VCAP_SERVICES` binding.
+See the [Identity Authentication Service](./ias#convenience-functions) documentation for details.
+
 If you want to skip the destination lookup and consider only the service bindings, call the [getDestinationFromServiceBinding()](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.getDestinationFromServiceBinding.html) function with the service name and options.
 
 ```ts

docs-js/features/connectivity/ias.mdx

@@ -81,12 +81,16 @@ sequenceDiagram
 
 ### Creating Destinations
 
-Use [`getDestinationFromServiceBinding()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.getDestinationFromServiceBinding.html) to connect to a system that is registered as an application within IAS.
+Use [`getDestinationFromServiceBinding()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.getDestinationFromServiceBinding.html) or [`transformServiceBindingToDestination()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.transformServiceBindingToDestination.html) to connect to a system that is registered as an application within IAS.
 The parameter `iasOptions` contains:
 
 - `targetUrl`: The URL of the system where the target application resides.
 - `resource`: The dependency identified by its name or identifier configured in IAS (see [App2App Resources](#app2app-resources)) section.
 
+In addition to these standard functions for destination retrieval and transformation, the SAP Cloud SDK provides two convenience functions, [`getIasDestination()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.getIasDestination.html) and [`getIasToken()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.getIasToken.html), which fetch an IAS token and return a destination or token result respectively.
+These functions are useful when you need direct access to the IAS token or destination, for example outside BTP environments with pre-populated `VCAP_SERVICES` or when constructing a destination manually.
+Refer to the [Convenience Functions](#convenience-functions) section below for more details.
+
 #### Technical User Authentication
 
 For service-to-service communication with client credentials:
@@ -121,11 +125,6 @@ const destination = await getDestinationFromServiceBinding({
 
 #### Business User Authentication
 
-:::warning
-
-When using business user authentication, token requests are not cached.
-
-:::
 :::info
 
 Setting `authenticationType` to `OAuth2JWTBearer` is required to trigger Business User authentication.
@@ -246,3 +245,63 @@ const destination = await getDestinationFromServiceBinding({
 });
 // Token request is automatically routed to the subscriber's IAS tenant
 ```
+
+## Convenience Functions
+
+The SAP Cloud SDK provides two convenience functions for working with IAS tokens directly.
+These are useful when you need access to the IAS token or destination, for example outside BTP environments with pre-populated `VCAP_SERVICES` or when constructing a destination manually.
+
+Both functions accept a service as `Service | string | ServiceCredentials`, unlike `getDestinationFromServiceBinding()` they also accept bare `ServiceCredentials` (e.g., just `clientid`, `clientsecret`, and `url`).
+
+- **[`getIasDestination()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.getIasDestination.html)** fetches an IAS token and builds a ready-to-use [`Destination`](pathname:///api/v4/interfaces/sap-cloud-sdk_connectivity.Destination.html) with the token, the target URL, and the mTLS key pair from the service binding credentials (if present).
+- **[`getIasToken()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.getIasToken.html)** fetches an IAS token and returns an [`IasTokenResult`](pathname:///api/v4/interfaces/sap-cloud-sdk_connectivity.IasTokenResult.html) with the access token string, its expiration, and an optional refresh token.
+
+:::note
+
+`getIasToken()` returns the access token as a raw string rather than a decoded JWT, as IAS tokens may not always be in JWT format.
+
+:::
+
+:::note
+
+The `targetUrl` is ignored if `getIasToken()` is used.
+
+:::
+
+```typescript
+import { getIasDestination, getIasToken } from '@sap-cloud-sdk/connectivity';
+
+// Use getIasDestination() to build a destination (technical user)
+const destination = await getIasDestination(
+  {
+    clientid: 'CLIENT_ID',
+    clientsecret: 'CLIENT_SECRET',
+    url: 'https://my-ias.accounts.ondemand.com'
+  },
+  {
+    targetUrl: 'https://backend-provider.example.com',
+    jwt: JWT_PAYLOAD,
+    requestAs: 'current-tenant',
+    resource: { name: 'backend-api' }
+  }
+);
+
+// Use getIasToken() to retrieve an IAS token (business user)
+const token = await getIasToken(
+  {
+    clientid: 'CLIENT_ID',
+    clientsecret: 'CLIENT_SECRET',
+    url: 'https://my-ias.accounts.ondemand.com'
+  },
+  {
+    authenticationType: 'OAuth2JWTBearer',
+    assertion: JWT_ASSERTION,
+    resource: { name: 'backend-api' }
+  }
+);
+```
+
+The `Destination` returned by `getIasDestination()` can be passed directly to any SAP Cloud SDK request builder or HTTP client.
+
+For the full set of options both functions accept the same [`IasTokenOptions`](pathname:///api/v4/types/sap-cloud-sdk_connectivity.IasTokenOptions.html) which includes `iasOptions` properties as available in [`getDestinationFromServiceBinding()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.getDestinationFromServiceBinding.html) or [`transformServiceBindingToDestination()`](pathname:///api/v4/functions/sap-cloud-sdk_connectivity.transformServiceBindingToDestination.html).
+See the [App2App Authentication](#app2app-authentication) section above for details.