Fatfree Templating error in AJAX

Question

I want to make a dynamic page which call ajax when link is clicked and this is my code

$(window).load(function(){
    $.ajax({
        url: BASE + '/ui/' + pageStates[state],
        dataType: 'html',
        success: function(res){
            $('#main__window').append(res);
        }
    });
});

URL link which I fired contains fatfree templating like {{@BASE}}, as you can see below

<a data-item-image='{{@BASE}}/ui/images/item_hariette.jpg' </a>

It's not decoded and I got this error in console

Thank you..