Как вызвать функцию codeigniter в цикле ajax

Question

В моем коде AJaX я хочу использовать функцию CodeIgniter

<?php echo $controller->timestamp(data[i].published);?>

Но она не работает

function show_draft(){
    $.ajax({
        type: 'ajax',
        url: '<?php echo base_url() ?>ct_backend/show_draft',
        async: false,
        dataType: 'json',               
        success: function(data){
            var html = '';
            var i;
            for(i=0; i<data.length; i++){

                html +='<div class="media dashboard-draft-each">'+
                '<div class="media-body custom-form-button">'+
                '<ul>'+
                '<li class="dropdown">'+
                '<a href="#" class="nav-link" data-toggle="dropdown">'+
                '<span class="fa fa-ellipsis-h"></span>'+
                '</a>'+
                '<div class="dropdown-menu">'+
                '<a href="javascript:;" class="dropdown-item draft-edit" data="'+data[i].id+'"><span class="fa fa-pencil-alt"></span> Edit</a>'+
                '<a href="javascript:;" class="dropdown-item draft-delete" data="'+data[i].id+'"><span class="fa fa-trash"></span> Delete</a>'+
                '</div>'+
                '</li>'+
                '</ul>'+
                '<a href="javascript:;" data="'+data[i].id+'">'+data[i].name+'</a>'+
                '<p>'+data[i].description+'</p>'+
                '<span class="far fa-clock"> '+<?php echo $controller->timestamp(data[i].published);?>+'</span>'+
                '</div>'+
                '</div>';                                       
            }
            $('#show_draft').html(html);
        },
        error: function(){
            Toast();
            function Toast (){
                var priority = 'danger';
                var title    = 'Error';
                var message  = 'Could not get Data from Database!';
                $.toaster({ priority : priority, title : title, message : message });
            }
        }
    });
}//end Show draft