<input id="fullname" name="fullname" type="text" />
<link href="https://cdn.jsdelivr.net/npm/@dadata/suggestions@25.8.0/dist/suggestions.min.css" rel="stylesheet" />
<script src="https://cdn.jsdelivr.net/npm/@dadata/suggestions@25.8.0/dist/suggestions.min.js"></script>

const input = document.getElementById("address");
Dadata.createSuggestions(input, {
    serviceUrl: "http://ВАШ_СЕРВЕР:ПОРТ/suggestions/api/4_1/rs",
    type: "name",
    // Вызывается, когда пользователь выбирает одну из подсказок
    onSelect: function (suggestion) {
        console.log(suggestion);
    }
});