Complete Accelerometer.js code

accelerometer.js

/**
 * An accelerometer object for detecting device orientation
 *  and motion (if supported)
 * 
 * Chrome 7+, Firefox 6+, IE11+, iOS Safari 4.0+, Android Browser 3.0, Blackberry 10.0
 *   http://caniuse.com/#feat=deviceorientation
 *   
 *   The DeviceOrientationEvent.alpha value represents the motion of the device around the z axis,
 *    represented in degrees with values ranging from 0 to 360.
 *    
 *    The DeviceOrientationEvent.beta value represents the motion of the device around the x axis,
 *    represented in degrees with values ranging from -180 to 180. 
 *    This represents a front to back motion of the device.
 *    
 *    The DeviceOrientationEvent.gamma value represents the motion of the device around the y axis,
 *    represented in degrees with values ranging from -90 to 90. 
 *    This represents a left to right motion of the device.
 *    
 * @property {boolean} supported If orientation events are supported in the current context
 */

var Accelerometer = function() {
  var self = this;
  self.supported = false;
  var absolute = null,
      alpha = null,
      beta = null,
      gamma = null,
      acceleration = null,
      accelerationIncludingGravity = null,
      rotationRate = null,
      interval = null;
      
  self.getAlpha = function() {
    return (alpha !== null) ? alpha : 0;
  };
  self.getBeta = function() {
    return (beta !== null) ? beta : 0;
  };
  self.getGamma = function() {
    return (gamma !== null) ? gamma : 0;
  };
  self.getAcceleration = function() {
    return (acceleration !== null) ? acceleration : 0;
  };
  self.getAccelerationIncludingGravity = function() {
    return (accelerationIncludingGravity !== null) ? accelerationIncludingGravity : 0;
  };
  self.getRotationRate = function() {
    return (rotationRate !== null) ? rotationRate : 0;
  };
  self.getInterval = function() {
    return (interval !== null) ? interval : 0;
  };

  if (!!window.DeviceMotionEvent) {
    window.addEventListener("devicemotion", handleMotion, true);
    self.supported = true;
  }
  if (!!window.DeviceOrientationEvent) {
    window.addEventListener("deviceorientation", handleOrientation, true);
    self.supported = true;
  }

  window.addEventListener("compassneedscalibration", function(event) {
    self.supported = true;
    alert('Your compass needs calibrating!');
    event.preventDefault();
  }, true);

  function handleOrientation(event) {
    absolute = event.absolute;
    alpha = event.alpha;
    beta = event.beta;
    gamma = event.gamma;
  }
  function handleMotion(event) {
    acceleration = accelerationIncludingGravity = rotationRate = {};
    acceleration.x = event.acceleration.x;
    acceleration.y = event.acceleration.y;
    acceleration.z = event.acceleration.z;
    accelerationIncludingGravity.x = event.accelerationIncludingGravity.x;
    accelerationIncludingGravity.y = event.accelerationIncludingGravity.y;
    accelerationIncludingGravity.z = event.accelerationIncludingGravity.z;
    rotationRate.alpha = event.rotationRate.alpha;
    rotationRate.beta = event.rotationRate.beta;
    rotationRate.gamma = event.rotationRate.gamma;
    interval = event.interval;
  }
};