iu9-ca-web-chat/assets/js/registration.js

document.addEventListener('DOMContentLoaded', function() {
        const form = document.querySelector('form');
        const submitButton = form.querySelector('button[type="submit"]');
        const errorElement = document.getElementById('error');

        form.addEventListener('keydown', function(event) {
            const activeElement = document.activeElement;
            const formElements = Array.from(form.elements);
            const currentIndex = formElements.indexOf(activeElement);

            if (activeElement.tagName === 'INPUT') {
                if (event.key === 'Enter') {
                    event.preventDefault();
                    if (currentIndex === formElements.length - 1) {
                        submitButton.focus();
                    } else if (currentIndex !== -1 && formElements[currentIndex + 1]) {
                        formElements[currentIndex + 1].focus();
                    }
                }
            }
        });

        submitButton.addEventListener('focus', function() {
            submitButton.classList.add('focus-visible');
        });

        submitButton.addEventListener('blur', function() {
            submitButton.classList.remove('focus-visible');
        });

        form.addEventListener('submit', function(event) {
            if (!validateForm()) {
                event.preventDefault();
            }
        });

        function validateForm() {
            const username = document.getElementById('username').value.trim();
            const login = document.getElementById('login').value.trim();
            const password = document.getElementById('password').value.trim();

            if (username === '' || login === '' || password === '') {
                errorElement.textContent = 'Пожалуйста, заполните все поля';
                errorElement.style.display = 'block';
                return false;
            }

            return true;
        }
    });