Since iOS 11, turning Bluetooth off from the control center only puts Bluetooth on a timeout until the next morning instead of disabling it permanently, as one would expect. Even when it’s off, the antenna stays on, looking for new devices. You can turn it all the way off by digging into the settings menu, but as soon as you turn it on for any reason, the cycle starts again.
JQuery would make sense when we didn’t have querySelector and fetch API. I can’t think of any reason to use it today on a new project, there are not advantages over vanilla.