Try this:
$('element').attr('id', 'value');
So it becomes;
$(function() {
$('span .breadcrumb').each(function(){
$('#nav').attr('id', $(this).text());
$('#container').attr('id', $(this).text());
$('.stretch_footer').attr('id', $(this).text())
$('#footer').attr('id', $(this).text());
});
});
So you are changing/overwriting the id of three elements and adding an id to one element. You can modify as per you needs…