Why doesn't jQuery's document.on('click') fire on iOS?

Question

JavaScript

Hello guys. Tell me, who knows the reason, or who has come across why the on event does not fire in this example:

$(document).on('click', '.poster', function(e) {
  e=e||window.event;
  var target=e.target||e.srcElement;
  if( $(e).parents('.opened').length ) return;
  $(this).parents('.item').addClass('opened');
});

Everywhere works, in iOS for some reason refuses.

Answer 1

What is e ??

e=e||window.event;
  var target=e.target||e.srcElement;