JsHost Class

HostCallJobCallback(jobCallback, V, argumentsList) for the handlers created by the engine whose [[HostDefined]] value (JsHost.MakeContinuationHostDefined) is not null: calls JsContinuation.Invoke, restoring the host-defined state.

HostCallJobCallback(jobCallback, V, argumentsList): calls the callback, restoring the host-defined state captured by JsHost.MakeJobCallback.

HostEnqueueGenericJob(job, realm): e.g. the cleanup of a FinalizationRegistry, or the resolution of the promise of Atomics.waitAsync. It can be called from any thread (the finalizer thread, the thread of another agent). The default implementation adds the job to the queue of the engine: JsEngine.RunJobs runs it.

HostEnqueueTimeoutJob(timeoutJob, realm, milliseconds): e.g. the timeout of Atomics.waitAsync. The default implementation runs the job from JsEngine.RunJobs once the delay has elapsed (measured with the JsEngineOptions.TimeProvider).

HostEnsureCanCompileStrings: throws (e.g. an EvalError) when the host forbids the compilation of the code (a content security policy).

HostGetCodeForEval(argument): the code of a value given to eval (a string; the host may accept other objects, e.g. a TrustedScript), or null.

HostMakeJobCallback(callback) for the handlers that the engine creates without a function object (the continuations of await, of the async generators, of the module loading...): returns the [[HostDefined]] value, which JsHost.CallContinuation restores when the handler runs, or null when there is no state to restore (the default: the handler is then called directly).

HostMakeJobCallback(callback): called when a callback is registered (e.g. by then), to capture a host-defined state (e.g. the incumbent settings object).

HostPromiseRejectionTracker(promise, operation). The default implementation does nothing.

Reports the exception thrown by a job (HostReportErrors). The default implementation rethrows it: it propagates out of JsEngine.RunJobs, and the other jobs stay in the queue.