Comment by livre

If you mean multithreaded as running separate OS threads I've got to agree with you but the definition of thread isn't limited to just that. I don't know about the internals of web browsers or whether they use OS threads or green threads or a combination of both for web workers but they are threads and that's how the MDN calls them too: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers...