Admits any value exposing a then() method, whatever its provenance, so that a possibly asynchronous value is told
apart from a settled one without ruling out foreign promise implementations; nothing beyond then() is guaranteed,
and isPromise is required where catch() and finally() are also relied on.
Checks if a value is thenable.
Admits any value exposing a
then()method, whatever its provenance, so that a possibly asynchronous value is told apart from a settled one without ruling out foreign promise implementations; nothing beyondthen()is guaranteed, and isPromise is required wherecatch()andfinally()are also relied on.