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PerformanceResourceTiming.requestStart

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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.

There is no end property for requestStart.

This property is Read only .

Syntax

resource.requestStart;

Return value

A DOMHighResTimeStamp representing the time immediately before the bowser starts requesting the resource from the server

Example

In the following example, the value of the *Start and *End properties of all "resource" type events are logged.

function print_PerformanceEntries() {
  // Use getEntriesByType() to just get the "resource" events
  var p = performance.getEntriesByType("resource");
  for (var i=0; i < p.length; i++) {
    print_start_and_end_properties(p[i]);
  }
}
function print_start_and_end_properties(perfEntry) {
  // Print timestamps of the PerformanceEntry *start and *end properties 
  properties = ["connectStart", "connectEnd",
                "domainLookupStart", "domainLookupEnd",
                "fetchStart", 
                "redirectStart", "redirectEnd",
                "requestStart", 
                "responseStart", "responseEnd",
                "secureConnectionStart"];

  for (var i=0; i < properties.length; i++) {
    // check each property
    var supported = properties[i] in perfEntry;
    if (supported) {
      var value = perfEntry[properties[i]];
      console.log("... " + properties[i] + " = " + value);
    } else {
      console.log("... " + properties[i] + " = NOT supported");
    }
  }
}

Specifications

Specification Status Comment
Resource Timing
The definition of 'requestStart' in that specification.
Editor's Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support. 43 40 10 32 No support
Feature Android Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support. 4.4 42 ? 10.0 32 No support

Document Tags and Contributors

 Contributors to this page: rolfedh, AFBarstow
 Last updated by: rolfedh,