If you've ever experimented with the navigation and resource timing APIs in the browser, it can be a daunting task to understand the performance timings they provide. What's the difference between
fetchStart? Where does SSL time figure in? What the heck does
domInteractive mean, and how is that different from
domComplete? What order do these timings even occur in?
This specification defines an interface for web applications to access the complete timing information for navigation of a document.
This specification defines an interface for web applications to access the complete timing information for page resources.
The PerformanceObserver interface is used to observe performance measurement events and be notified of new performance entries as they are recorded in the browser's performance timeline.