This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
read-only property returns an
unsigned long long representing the moment,
in milliseconds since the UNIX epoch, when the browser sent the request to obtain the
actual document, from the server or from a cache. If the transport layer fails after the
start of the request and the connection is reopened, this property will be set to the
time corresponding to the new request.
time = performanceTiming.requestStart;
The definition of 'PerformanceTiming.requestStart' in that specification.
BCD tables only load in the browser
PerformanceTiminginterface it belongs to.