如何检测JS/JQuery动态更改输入值的时间

var $val = $.fn.val;
$.fn.val = function(newVal) {
  if (this.attr('id') === 'target') this.trigger('input');
  $val.call(this, newVal);
}

$('#target').on('input', function() {
  alert("changed");
});

$('#target').val('Ele from Stack');
$('#target2').val('Ele from Stack2');

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<input id='target' />
<input id='target2' />

var $val = $.fn.val;
$.fn.val = function(newVal,eventToTrigger) {
  if (eventToTrigger != null) this.trigger(eventToTrigger);
  $val.call(this, newVal);
}

$('.someClass').on('input', function() {
  alert("Programmatically inputted!");
});

$('.otherClass').on('change', function() {
  alert("Programmatically changed!");
});

$('.someClass').val('Hello you!','input');
$('.otherClass').val('Doing fine?','change');
$('#whatever').val('Hehehe.');

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<input type="text" class="someClass">
<input type="text" class="otherClass">
<input type="text" id="whatever">