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.
Syntax
resource.workerStart;
Value
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 Level 2The definition of 'workerStart' in that specification. | Working Draft | Initial definition. |
Browser compatibility
The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
workerStart
|
Chrome
Full support 43 |
Edge
Full support 16 |
Firefox
Full support 58 |
IE
No support No |
Opera
Full support 32 |
Safari
Full support 11 |
WebView Android
Full support 43 |
Chrome Android
Full support 43 |
Firefox Android
Full support 58 |
Opera Android
Full support 32 |
Safari iOS
Full support 11 |
Samsung Internet Android
Full support 4.0 |
Legend
- Full support
- Full support
- No support
- No support
PerformanceResourceTiming.workerStart by Mozilla Contributors is licensed under CC-BY-SA 2.5.