printer.js

window["DatecsPrinter"].listBluetoothDevices(
  function (devices) {
    window["DatecsPrinter"].connect(devices[0].address, 
      function() {
        printSomeTestText();
      },
      function(error) {
        alert(JSON.stringify(error));
      }
    );
  },
  function (error) {
    alert(JSON.stringify(error));
  }
);

function printSomeTestText() {
  window["DatecsPrinter"].printText("Print Test!", 'ISO-8859-1', 
    function() {
      //printMyImage();
    }
  );
}