Class change watch width mutationObserver

function maintenanceAjaxLoad(clickedMenuItem){
    /* new logo position */
    var logo     = document.getElementById('ufk__animated');
    var mainCont = document.getElementById('mainContent');
    var ajaxHref = clickedMenuItem.href;
    var ajaxData = ajaxHref.replace(/(#[^-]+)/,'') + '.json';
    var ajaxCont = document.getElementById('bodyCont');

    const mutationObserver = new MutationObserver(function (mutationsList, observer) {
        mutationsList.forEach(mutation => {
            console.log(mutation.target);

            if (mutation.target.classList.contains('finished')) {
                console.log('finished' + logo);

                logo.classList.add('ufk_newpos');

                logo.addEventListener('animationend', function(){
                    logo.classList.replace('finished', 'anicomplete');

                    mainCont.style.flex = '1 0 auto';
                    mainCont.style.justifyContent = 'flex-start';

                    ajaxCont.classList.add('fade-in');

                    ajaxLoad(ajaxData, ajaxCont, function(response){
                        let htmlTitle = response.title;
                        let htmlText = response.text;

                        ajaxCont.innerHTML = htmlTitle + htmlText;
                        history.pushState(htmlText, ajaxData, ajaxHref);
                    });
                });
            }
        });
    });

    mutationObserver.observe(logo, { attributes: true});

    if(logo.classList.contains('anicomplete')){
        ajaxLoad(ajaxData, ajaxCont, function(response){
            let htmlTitle = response.title;
            let htmlText = response.text;

            ajaxCont.innerHTML = htmlTitle + htmlText;
            history.pushState(htmlText, ajaxData, ajaxHref);
        });
    }
}