& isUsed === true) {

                registered.push(domain);

            } else if (domain && isUsed === null) {

                rate_limited = true;
                break;
            }

            await sleep(1000);

            i++;
        }

        $('.dns_checker').innerHTML = 'Check availability';

        if (rate_limited) {
            alert('Cannot check any domain availability as a rate limit occurred.');
        }

        if (registered.length != 0) {
            alert('The domain(s) ' + 