The correct way to get the id of the last child div inside parent container using jQuery:
<div id=container> <div id=box1></div> <div id=box2></div> <div id=box3></div> <div id=box4></div> <div id=box5></div> <div id=box6></div> </div>
$('#container').children().last().attr('id');
Or
var id = $('#container div:last').attr('id')
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