code: function (e) {
                  if (e.targetTouches.length < 2) return 1;
                  var x1 = e.targetTouches[0].pageX,
                      y1 = e.targetTouches[0].pageY,
                      x2 = e.targetTouches[1].pageX,
                      y2 = e.targetTouches[1].pageY;
                  var distance = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2));
                  return distance;
              }
docs: Calc Scale From Multi-touches