code: function getPointerType( event ) {
          var pointerTypeStr;
          if ( $.MouseTracker.unprefixedPointerEvents ) {
              pointerTypeStr = event.pointerType;
          } else {
              // IE10
              //  MSPOINTER_TYPE_TOUCH: 0x00000002
              //  MSPOINTER_TYPE_PEN:   0x00000003
              //  MSPOINTER_TYPE_MOUSE: 0x00000004
              switch( event.pointerType )
              {
                  case 0x00000002:
                      pointerTypeStr = 'touch';
                      break;
                  case 0x00000003:
                      pointerTypeStr = 'pen';
                      break;
                  case 0x00000004:
                      pointerTypeStr = 'mouse';
                      break;
                  default:
                      pointerTypeStr = '';
              }
          }
          return pointerTypeStr;
      }
docs: Gets a W3C Pointer Events model compatible pointer type string from a DOM pointer event.
  IE10 used a long integer value, but the W3C specification (and IE11+) use a string "mouse", "touch", "pen", etc.
  @private
  @inner