Build a client side Analytics Library for tracking events

Clarifying Questions

• How will this library be loaded in the browser?
• What kind of events should be tracked?
• What is the expected volume of events?
• Should the library support batching of events or send events immediately?
• Should the tracking persist across browser reloads?
• Should we handle retries on failed network calls?

Explanation

This is a client-side analytics library built in javascript that can batch events, retry on failure, and persist them in localStorage. It ensures reliability using `navigator.sendBeacon` during page unload and attempts to resend failed events with a configurable retry limit. The design emphasizes reliability and fault tolerance in a minimal analytics tracking setup.

Solution Code

Scale-Ups

• Implement batching of events to reduce network calls
• Add retry logic for failed API calls with a configurable retry limit
• How can we ensure that event data is not lost on page reloads or navigation?
• How can we minimize the impact of the library on page performance?

Interviewer's Expectations

• Queue events and persist them using localStorage
• Batch and send events at regular intervals
• Retry failed API calls with a retry limit
• Use navigator.sendBeacon on page unload to ensure no data loss
• Ensure the library can handle high event volumes efficiently
• Include unit tests to validate the functionality of the library