gesture.js

//     Zepto.js
//     (c) 2010-2015 Thomas Fuchs
//     Zepto.js may be freely distributed under the MIT license.

;(function($){
  if ($.os.ios) {
    var gesture = {}, gestureTimeout

    function parentIfText(node){
      return 'tagName' in node ? node : node.parentNode
    }

    $(document).bind('gesturestart', function(e){
      var now = Date.now(), delta = now - (gesture.last || now)
      gesture.target = parentIfText(e.target)
      gestureTimeout && clearTimeout(gestureTimeout)
      gesture.e1 = e.scale
      gesture.last = now
    }).bind('gesturechange', function(e){
      gesture.e2 = e.scale
    }).bind('gestureend', function(e){
      if (gesture.e2 > 0) {
        Math.abs(gesture.e1 - gesture.e2) != 0 && $(gesture.target).trigger('pinch') &&
          $(gesture.target).trigger('pinch' + (gesture.e1 - gesture.e2 > 0 ? 'In' : 'Out'))
        gesture.e1 = gesture.e2 = gesture.last = 0
      } else if ('last' in gesture) {
        gesture = {}
      }
    })

    ;['pinch', 'pinchIn', 'pinchOut'].forEach(function(m){
      $.fn[m] = function(callback){ return this.bind(m, callback) }
    })
  }
})(Zepto)