The standalone telemetry JS library allows users to capture telemetry data without the restrictions of using any app that uses the Genie SDK, the EkStep content player or the EkStep or Sunbird portal. Partner users can use the JS library to log and sync telemetry data. They can decide how to use the Telemetry JS library, and integrate it with their app, webpage or web service
Standalone JS Library section will help you in understanding better how JS library serves the purpose of capturing telemetry data
HTML Interface Library
The ContentRenderer handles telemetry events for ECML content. HTML content has functionality such as click, navigation, assessment, etc. These functionalities are specific to or different for individual HTML content pieces.