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PerformanceResourceTiming.workerStart

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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.

This property is Read only .

Syntax

resource.workerStart;

Return value

If the current context is a worker, returns the DOMHighResTimeStamp immediately before the worker is started that fetches the resource; otherwise, the timestamp is zero.

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",
		"workerStart"];

  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 'workerStart' in that specification.
Editor's Draft Initial definition.

Browser compatibility

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

Document Tags and Contributors

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