The responseEnd property returns a timestamp immediately after the browser receives the last byte of the resource or immediately before the transport connection is closed, whichever comes first.
The responseStart property returns a timestamp immediately after the browser receives the first byte of the response from the server, cache, or local resource.
The secureConnectionStart property returns a timestamp immediately before the browser starts the handshake process to secure the current connection. If a secure connection is not used, the property returns zero.
The transferSize property represents the size (in octets) of the fetched resource. The size includes the response header fields plus the response payload body (as defined by RFC7230.
If the current context is a worker, the workerStart property returns a timestamp immediately before the worker that fetches the resource is started. If the context is not a worker (i.e. a browser context), this property returns zero.
The observe() method of the PerformanceObserver interface is used to specify the set of performance interface types to observe. The performance observer's callback function will be invoked when a performance entry is recorded for one of the specified types.
The PerformanceObserver() constructor creates a new PerformanceObserver object with the given observer callback. The observer callback is invoked when performance entry events are recorded for the entry types that have been registered, via the observe() method.
The getEntries() method of the PerformanceObserverEntryList interface returns a list of explicitly observedperformance entry objects for a given filter. The list's members are determined by the set of entry types specified in the call to the observe() method. The list is available in the observer's callback function (as the first parameter in the callback).
The getEntriesByName() method of the PerformanceObserverEntryList interface returns a list of explicitly observedperformance entry objects for a given name and entry type. The list's members are determined by the set of entry types specified in the call to the observe() method. The list is available in the observer's callback function (as the first parameter in the callback).
The getEntriesByType() method of the PerformanceObserverEntryList returns a list of explicitly observedperformance entry objects for a given performance entry type. The list's members are determined by the set of entry types specified in the call to the observe() method. The list is available in the observer's callback function (as the first parameter in the callback).
The Navigator interface represents the state and the identity of the user agent. It allows scripts to query it and to register themselves to carry on some activities.
The PerformanceTiming.navigationStart read-only property returns an unsigned long long representing the moment, in miliseconds since the UNIX epoch, right after the prompt for unload terminates on the previous document in the same browsing context. If there is no previous document, this value will be the same as PerformanceTiming.fetchStart.