The unloadEventEnd property returns a timestamp representing the time value equal to the time immediately after the user agent finishes the unload event of the previous document. If there is no previous document, this property value is 0.
The unloadEventStart property returns a timestamp representing the time value equal to the time immediately before the user agent starts the unload event of the previous document. If there is no previous document, this property returns 0.
The PerformanceResourceTiming interface enables retrieving and analyzing detailed network timing data regarding the loading of an application's resources. An application can use the timing metrics to determine, for example, the length of time it takes to fetch a specific resource, such as an XMLHttpRequest, <SVG>, image, or script.
The connectEnd property returns the timestamp immediately after the browser finishes establishing the connection to the server to retrieve the resource. The timestamp value includes the time interval to establish the transport connection, as well as other time intervals such as SSL handshake and SOCKS authentication.
The decodedBodySize property returns the size (in octets) received from the fetch (HTTP or cache) of the message body, after removing any applied content-codings. If the resource is retrieved from an application cache or local resources, it returns the size of the payload after removing any applied content-codings.
The requestStart property returns a timestamp of the time immediately before the browser starts requesting the resource from the server, cache, or local resource. If the transport connection fails and the browser retires the request, the value returned will be the start of the retry request.