HTML, custom element attribute, will work on all browsers?
<div id="c" my-custom-attr="myValue" data-my-custom-attr="another-value">
    Content here
</div>

<script type="text/javascript">
    $att1 = $('#c').attr('my-custom-attr');
    $att2 = $('#c').attr('data-my-custom-attr');
</script>

<div id="c" data-my-custom-attr="another-value">
    Content here
</div>

<script type="text/javascript">
    // Both produce the same output //
    console.log($('#c').attr('data-my-custom-attr'));
    console.log($('#c').data('my-custom-attr'));
</script>