<div id="123" data-img-flag="1">
<image src="abc.png">
</div>
<div id="432" data-img-flag="0">
<image src="abc.png">
</div>
<script>
alert($(popImgId).data('img-flag')); // when we use data function to get the data attribute value wll get all time value loaded at the time of DOM loaded
alert($(popImgId).attr('data-img-flag')); // value will get lates. If we change/update value using jquery will get updated value
</script>
//get the result as array
<option value="<?php echo $value['id']; ?>" data-count="5">
</option>
var data = $('.myclass').map(function() {
return $(this).data('optionid');
}).get();