Case 7 :
Web Developer declared only footer in page
but need to add back button dynamically in header
select header and call barlayout("addBackBtn") API
<div data-role="page" data-add-back-btn="none">
    <div data-role="header" data-position="fixed">
        <h1>back button sample</h1>
    </div>
    <div data-role="content">
    </div>
    <div data-role="footer">
    </div>
</div>
<script>
var $elHeader = $(".ui-page-active").find(".ui-header");
$elHeader.barlayout("addBackBtn");
</script>