Any standard mechanism for detecting if a JavaScript is executing as a WebWorker?

Question

A WebWorker executes with a scope completely separate from the \'window\' context of traditional JavaScript. Is there a standard way for a script to determine if it is, its

Answer 1

There's even more: WorkerNavigator etc.

Unless there's a keyword to detect webworkers, you got to use a variable. (Nothing can stop a rogue script running before your script from setting or replacing variables. )

So, assuming you do not have any rogue scripts running before your script, any of these lines will work:

this.DedicatedWorkerGlobalScope?this.__proto__ === this.DedicatedWorkerGlobalScope.prototype:false

this.WorkerGlobalScope?this.__proto__.__proto__ === this.WorkerGlobalScope.prototype:false // works for shared workers too

this.constructor === this.DedicatedWorkerGlobalScope //or SharedWorkerGlobalScope

!(this.DedicatedWorkerGlobalScope === undefined)

!(this.DedicatedWorkerGlobalScope === undefined)

You can also use self § instead of this, but since this can't be set, its neater.

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I prefer:

this.DedicatedWorkerGlobalScope !== undefined

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Of course, if you only have worker context and window context, you can do the inverse tests for window context. Eg this.Window === undefined.