Function on

on(
    event:
        | "change"
        | "screensDidSleep"
        | "screensDidWake"
        | "screensDidLock"
        | "screensDidUnlock"
        | "screensaverDidStart"
        | "screensaverDidStop"
        | "screensaverWillStop"
        | "systemWillSleep"
        | "systemDidWake"
        | "systemWillPowerOff"
        | "sessionDidBecomeActive"
        | "sessionDidResignActive",
    listener: () => void,
): void
Register a listener for system power/session events, or battery state changes.
Parameters
- event:
      | "change"
      | "screensDidSleep"
      | "screensDidWake"
      | "screensDidLock"
      | "screensDidUnlock"
      | "screensaverDidStart"
      | "screensaverDidStop"
      | "screensaverWillStop"
      | "systemWillSleep"
      | "systemDidWake"
      | "systemWillPowerOff"
      | "sessionDidBecomeActive"
      | "sessionDidResignActive"
  The event to listen for. "change" fires whenever battery state changes; the rest are system power/session events.
- listener: () => void
  Called with no arguments when the event occurs; call batteryInfo() inside a "change" listener to inspect the new battery state
Returns void