The performance read-only property of the WorkerGlobalScope interface returns a Performance object to be used on the worker.
Not all Performance properties and methods are available to Web workers.
This property is Read only .
var perfObj = self.performance;
A Performance object.
If you called
console.log(performance);
inside a worker (which would basically be the equivalent of self.console.log(self.performance);, as these are being called on the worker scope, which can be referenced with WorkerGlobalScope.self), you will get a WorkerPerformance object written to the console — something like the following:
WorkerPerformance {now: function}
  __proto__: WorkerPerformance
    constructor: function WorkerPerformance() { [native code] }
    now: function now() { [native code] }
    __proto__: Object You could use this performance object to return performance data, as you might do with a normal Performance object.
Note: Firefox has a bug with using console.log inside shared/service workers (see bug 1058644), which may return strange results, but this should be fixed soon.
| Specification | Status | Comment | 
|---|---|---|
| High Resolution Time Level 2 The definition of 'performance' in that specification.  |  Candidate Recommendation | Defines WorkerGlobalScope.performance. | 
| Desktop | ||||||
|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | |
| Basic support | Yes | ? | 34 | ? | ? | ? | 
| Mobile | |||||||
|---|---|---|---|---|---|---|---|
| Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | iOS Safari | Samsung Internet | |
| Basic support | ? | Yes | ? | 34 | ? | ? | Yes | 
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    https://developer.mozilla.org/en-US/docs/Web/API/WorkerGlobalScope/performance