PerformanceResourceTiming.workerStart
The workerStart
read-only property of the
PerformanceResourceTiming
interface 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.
Note: This feature is available in Web Workers
Value
Examples
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 |
---|
Resource Timing Level 2 # dom-performanceresourcetiming-workerstart |
Browser compatibility
BCD tables only load in the browser