PerformanceResourceTiming

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The PerformanceResourceTiming interface enables retrieval and analysis of 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 interface's properties create a resource loading timeline with high-resolution timestamps for network events such as redirect start and end times, fetch start, DNS lookup start and end times, response start and end times, etc.. Additionally, the interface extends PerformanceEntry with other properties which provide data about the size of the fetched resource as well as the type of resource that initiated the fetch.

Note: This feature is available in Web Workers.

Properties

This interface extends the following PerformanceEntry properties for resource performance entry types by qualifying and constraining them as follows:

 PerformanceEntry.entryTypeRead only
Returns "resource".
PerformanceEntry.nameRead only
Returns the resources URL.
PerformanceEntry.startTimeRead only
Returns the timestamp for the time a resource fetch started. This value is equivalent to PerformanceEntry.fetchStart.
PerformanceEntry.durationRead only
Returns a timestamp that is the difference between the responseEnd and the startTime properties.

The interface also supports the following properties which are listed in the order in which they are recorded for the fetching of a single resource. An alphabetical listing is shown in the navigation, at left.

PerformanceResourceTiming.initiatorTypeRead only
A string representing the type of resource that initiated the performance entry, as specified in PerformanceResourceTiming.initiatorType.
PerformanceResourceTiming.nextHopProtocolRead only
A string representing the network protocol used to fetch the resource, as identified by the ALPN Protocol ID (RFC7301).
PerformanceResourceTiming.workerStartRead only
Returns a DOMHighResTimeStamp immediately before dispatching the FetchEvent if a Service Worker thread is already running, or immediately before starting the Service Worker thread if it is not already running. If the resource is not intercepted by a Service Worker the property will always return 0.
PerformanceResourceTiming.redirectStartRead only
A DOMHighResTimeStamp that represents the start time of the fetch which initiates the redirect.
PerformanceResourceTiming.redirectEndRead only
A DOMHighResTimeStamp immediately after receiving the last byte of the response of the last redirect.
PerformanceResourceTiming.fetchStartRead only
A DOMHighResTimeStamp immediately before the browser starts to fetch the resource.
PerformanceResourceTiming.domainLookupStartRead only
A DOMHighResTimeStamp immediately before the browser starts the domain name lookup for the resource.
PerformanceResourceTiming.domainLookupEndRead only
A DOMHighResTimeStamp representing the time immediately after the browser finishes the domain name lookup for the resource.
PerformanceResourceTiming.connectStartRead only
A DOMHighResTimeStamp immediately before the browser starts to establish the connection to the server to retrieve the resource.
PerformanceResourceTiming.connectEndRead only
A DOMHighResTimeStamp immediately after the browser finishes establishing the connection to the server to retrieve the resource.
PerformanceResourceTiming.secureConnectionStartRead only
A DOMHighResTimeStamp immediately before the browser starts the handshake process to secure the current connection.
PerformanceResourceTiming.requestStartRead only
A DOMHighResTimeStamp immediately before the browser starts requesting the resource from the server.
PerformanceResourceTiming.responseStartRead only
A DOMHighResTimeStamp immediately after the browser receives the first byte of the response from the server.
PerformanceResourceTiming.responseEndRead only
A DOMHighResTimeStamp immediately after the browser receives the last byte of the resource or immediately before the transport connection is closed, whichever comes first.
PerformanceResourceTiming.transferSizeRead only
A number representing the size (in octets) of the fetched resource. The size includes the response header fields plus the response payload body.
PerformanceResourceTiming.encodedBodySizeRead only
A number representing the size (in octets) received from the fetch (HTTP or cache), of the payload body, before removing any applied content-codings.
PerformanceResourceTiming.decodedBodySizeRead only
A number that is the size (in octets) received from the fetch (HTTP or cache) of the message body, after removing any applied content-codings.
PerformanceResourceTiming.serverTimingRead only
An array of PerformanceServerTiming entries containing server timing metrics.

Methods

PerformanceResourceTiming.toJSON()
Returns a DOMString that is the JSON representation of the PerformanceResourceTiming object.

Example

See the example in Using the Resource Timing API.

Specifications

Specification Status Comment
Resource Timing Level 1
The definition of 'PerformanceResourceTiming' in that specification.
Candidate Recommendation Initial definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support43 Yes40103011
connectEnd431240103211
connectStart431240103211
decodedBodySize5417 No No41 No
domainLookupEnd431240 No3011
domainLookupStart431240 No3011
encodedBodySize5417 No No41 No
fetchStart431240 No3011
initiatorType431240 No3011
nextHopProtocol611751 No No No
redirectEnd431240 No3011
redirectStart431240 No3011
requestStart431240 No3011
responseEnd431240 No3011
responseStart431240 No3011
secureConnectionStart43 Yes40 No3011
serverTiming65 ?61 No52 ?
transferSize5417 No No41 No
workerStart431658 No3211
toJSON43 Yes40 No3011
Available in workers43 Yes60 No32 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support4343 Yes4230114.0
connectEnd4343 Yes4232114.0
connectStart4343 Yes4232114.0
decodedBodySize545417 No41 No6.0
domainLookupEnd4343 Yes4230114.0
domainLookupStart4343 Yes4230114.0
encodedBodySize545417 No41 No6.0
fetchStart4343 Yes4230114.0
initiatorType4343 Yes4230114.0
nextHopProtocol616117 No No No No
redirectEnd4343 Yes4230114.0
redirectStart4343 Yes4230114.0
requestStart4343 Yes4230114.0
responseEnd4343 Yes4230114.0
responseStart4343 Yes4230114.0
secureConnectionStart4343 Yes4230114.0
serverTiming6565 ?6152 ? ?
transferSize545417 No41 No6.0
workerStart4343 Yes5832114.0
toJSON4343 Yes4230114.0
Available in workers4343 Yes6032 No4.0

See also

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