(Information and examples taken from the DroidScript documentation)

The GetJoystickState method gets the state of a button or axis of a HID Joystick or Gamepad (For example, an Xbox 360 controller connected to your device via an OTG cable).

app.GetJoystickState( joyNum, keyName );

GetJoystickState can get the state of multiple HID controllers currently connected to your device. Pass 0 to GetJoystickState for the first controller, 1 for the second, etc.

The state of a button will be 1 if it is currently pressed, or 0 if not currently pressed.

For an axis, the return value will be in the range -1.0 to 1.0. For example, “axis-0” (the X-axis) will return -1.0 (fully left) to 1.0 (fully right).

function OnStart()
{
  lay = app.CreateLayout( "Linear", "VCenter,FillXY" );
 
  txt = app.CreateText( "", 1.0, -1, "MultiLine" );
  lay.AddChild( txt );
 
  app.AddLayout( lay );
 
  setInterval( ShowState, 200 );
}
 
function ShowState()
{
  var abtn = app.GetJoystickState( 0, "A" );
  var bbtn = app.GetJoystickState( 0, "B" );
  var xaxis = app.GetJoystickState( 0, "axis-0" );
  var yaxis = app.GetJoystickState( 0, "axis-1" );
 
  msg = "A:" + abtn + " B:" + bbtn + "\n";
  msg += " X-Axis:" + xaxis.toFixed(2) + " Y-Axis:" + yaxis.toFixed(2);
  txt.SetText( msg );
} 

Here is a list of the Joystick button names that can be passed to GetJoystickState:

The axis names can be “axis-0” to “axis-9”. “axis-0” and “axis-1” will in most cases be the X and Y axes of the HID controller's main analog stick (i.e. the left stick on an Xbox controller). The remaining axes are for other analog sticks and trigger buttons on the HID controller.