Detect when a puck.js disconnects from a browser form

Hello all,

I am a newbie and appreciate any help. I have tried generating a solution but have lost much hair trying!

I connect to the puck from a Windows browser using the following javascript function and query the accelerometer with a timer using the subsequent function. How can I detect if the puck.js disconnects?

Thanks in advance,

Jeff

// When we click the connect button...
    function connectclick() {
      Puck.write('Puck.accelOn(1.6);\n');
      Puck.write('NRF.setTxPower(4);\n');
      acceltimer = setInterval(accelcollect,650);
    }

    function accelcollect() {
      Puck.eval("Puck.accel()",function(x) {
        //Get accel data
        accel.x=x.acc.x;
        accel.y=x.acc.y;
        accel.z=x.acc.z;       
      })
    }