The devicechange event is fired when a media device (e.g., camera, microphone or speaker) is connected to or removed from the system. This feature is useful for applications that wish to react to changes in the set of available media devices; for example, to show a device list that is always up-to-date. This is expected to be on by default in Chrome 57.
Docs: https://developer.mozilla.org/en-US/docs/Web/Events/devicechange