JAVASCRIPT

check change event in jquery

<div class="form-group">
    <label class="w-20" id="loan_no_label"><?= "<font class='red'> * </font>" . __('loan-number') ?></label>
	<input class="w-65 form-control" id="loan_no" required type="text" name="loan_no" />
</div>

$('#is_all_loan').on('click', function() {

   var checked = $(this);
   if (checked.is(':checked')) {
     $('#loan_no_label').html('<?= __('loan-number'); ?>');
     $('#loan_no').attr('required', false); 

   } else {
     $('#loan_no_label').html("<font class='red'> * </font>貸款編號");
     $('#loan_no').attr('required', true); 
   }
 });

value change event jquery

$("#input").change(function(){
  alert("The text has been changed.");
});