"Uncaught TypeError: Cannot use 'in' operator to search for 'length' in" when getting checked values by data attribute

Question

This is the view of checkbox group

And this is my html code for the above view(there is more check boxes, only 2 mention here):

    <div class="panel-body subject_names">
   <div class="col-md-12">
      <label for="checkboxes-0" class="col-md-7">
      KE1-Financial Accounting &amp; Reporting Fundamen
      </label>
      <input type="checkbox" data-subject-name="KE1-Financial Accounting &amp; Reporting Fundamen" data-subject-ai="925" class="big-checkbox col-md-1 subject1" name="exam_subjects" id="checkboxes-0" value="1012"> 
      <div class="col-md-4 pull-left">
         <input id="training_institute" name="textinput" type="text" placeholder="" class="input-md">
      </div>
   </div>

   <div class="col-md-12">
      <label for="checkboxes-0" class="col-md-7">
      KE2-Management Accounting Information
      </label>
      <input type="checkbox" data-subject-name="KE2-Management Accounting Information" data-subject-ai="926" class="big-checkbox col-md-1 subject1" name="exam_subjects" id="checkboxes-0" value="1013"> 
      <div class="col-md-4 pull-left">
         <input id="training_institute" name="textinput" type="text" placeholder="" class="input-md">
      </div>
   </div>


</div>

and this is my js code :

var subjects_names = [];
$.each($("input[name='exam_subjects']:checked").attr("data-subject-name"), function() {
    subjects_names.push($(this).val());
});

Exception:

Exam_application_c:775 Uncaught TypeError: Cannot use 'in' operator to search for 'length' in KE1-Financial Accounting & Reporting Fundamen

Answer 1

You're using $.each on a string, it needs to be an object or an array.

Try changing your code to this

var subjects_names = [];
$.each($("input[name='exam_subjects']:checked"), function () {
    subjects_names.push($(this).data("subjectName"));
});

Or better yet use .each as your iterating over a jQuery object

var subjects_names = [];
$("input[name='exam_subjects']:checked").each(function () {
    subjects_names.push($(this).data("subjectName"));
});