code: function getDistance(touch1, touch2) {
        var x = touch2.pageX - touch1.pageX,
        y = touch2.pageY - touch1.pageY;
        return Math.sqrt((x*x) + (y*y));
      }
docs: calculate the distance between two touches
  @param   {Touch}     touch1
  @param   {Touch}     touch2
  @returns {Number}    distance