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 1 The definition of 'workerStart' in that specification. |
Candidate Recommendation | 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.
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 43 | 16 | 58 | No | 32 | 11 |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | Opera Android | iOS Safari | Samsung Internet |
---|---|---|---|---|---|---|---|
Basic support | 43 | 43 | Yes | 58 | 32 | 11 | 4.0 |