code: function () {
              // Sets properties of '_features' that change on resize and/or orientation.
              var w   = win.innerWidth || _viewport.clientWidth,
                  h   = win.innerHeight || _viewport.clientHeight,
                  dw  = win.screen.width,
                  dh  = win.screen.height,
                  c   = win.screen.colorDepth,
                  x   = win.devicePixelRatio;
  
              _features.width                     = w;
              _features.height                    = h;
              _features['aspect-ratio']           = (w / h).toFixed(2);
              _features['device-width']           = dw;
              _features['device-height']          = dh;
              _features['device-aspect-ratio']    = (dw / dh).toFixed(2);
              _features.color                     = c;
              _features['color-index']            = Math.pow(2, c);
              _features.orientation               = (h >= w ? 'portrait' : 'landscape');
              _features.resolution                = (x && x * 96) || win.screen.deviceXDPI || 96;
              _features['device-pixel-ratio']     = x || 1;
          }
docs: Internal globals