Solution: Track API Usage Metrics Transparently

Solution explanation

• Lines 2–10: We define the ApiService class that simulates two operations: fetchData() and postData().

  • These represent typical API calls whose usage frequency we want to monitor.

  • The goal is to track calls externally without changing the service implementation.

• Lines 13–37: The createTrackedService() function constructs a Proxy that adds a transparent tracking layer.

  • A target instance of ApiService is created as the real object.

  • A stats object stores call counts per method name. ...