var output = document.getElementById('server-log'); function reqListener() { var autoScroll = document.getElementById('auto-scroll'); output.textContent = xhr.responseText; if (autoScroll.checked) { output.scrollTop = output.scrollHeight; } } var xhr = new XMLHttpRequest(); xhr.addEventListener('load', reqListener); xhr.open('GET', '/server.log'); xhr.send(); setInterval(function() { xhr = new XMLHttpRequest(); xhr.addEventListener('load', reqListener); xhr.open('GET', '/server.log'); xhr.send(); }, 10000);