hero.js

'use strict';
    
var subjects = ['программирование', 'веб-разработку', 'HTML', 'CSS', 'JavaScript', 'React', 'Angular', 'Node.js'];
var element = $('#hero .subject');
var subjectIndex = 0;

(function printSubjects() {
    printSubject(subjects[subjectIndex])
        .then(function() {
            var timeout = setTimeout(function() {
                element.text(' ');
                subjectIndex === (subjects.length - 1) ? subjectIndex = 0 : subjectIndex += 1;
                clearTimeout(timeout);
                printSubjects();
            }, 1000);
        });
})();

function printSubject(subject) {
    return new Promise(function(resolve) {
        var index = 0;
        var interval = setInterval(function() {
            element.append(subject[index]);

            index += 1;

            if (index > subject.length) {
                clearInterval(interval);
                resolve();
            }
        }, 200);
    });
}