PerformanceResourceTiming.workerStart

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