Touchenter and touchleave events support

I suggest that you use

document.elementFromPoint(touch.x, touch.y);

on touchmove event.

There is a list here stating the version-wise compatibility. Currently Chrome, Opera, iOS Safari, Android Browser, Blackberry Browser, Opera Mobile, Chrome for Android, Firefox for android support this feature

W3C removed ontouchenter and ontouchleave, so that we can only do these(with zepto.js, touch.js, ontouchmove, elementFromPoint):

var last_touched_button='';
$('#container,#button1,#button2').on('touchmove',function(e){
      var ele=document.elementFromPoint(e.touches[0].clientX, e.touches[0].clientY);
      if (ele==document.getElementById('button1'))
      {last_touched_button='button1';
      }
      else if (ele==document.getElementById('button2'))
      {last_touched_button='button2';
      }
});
$('#container,#button1,#button2').on('swipeLeft',function(e){
      console.log('the button '+last_touched_button+' triggered swipe_into_left_side event or swipe_out_from_left_side event!');
});

You're referencing an old draft, the latest one removed the touchenter and touchleave events.