Testing for bluetooth connection

Thanks for your help.

I've found a workaround, it functions, but its not ideal and I doubt it's very efficient in terms of battery power. I check the RSSI (Signal Strength), and illuminate the LED depending on the result:

NRF.setRSSIHandler(function(rssi) {
  sigStrength = rssi;
});

function checkRssi() {
if (sigStrength > -51){
  digitalWrite(LED1,1);
}
else {digitalWrite(LED1,0);
}
}
  
function myFunction() {
  myVar = setInterval(checkRssi, 3000);
}
  
myFunction();