```javascript document.addEventListener("DOMContentLoaded", function(event) { // get #in and #out textareas var inText = document.getElementById('in'); var outText = document.getElementById('out'); // when #in textarea is changed, update #out textarea inText.addEventListener('input', function() { outText = btoa(inText); }); // when #out textarea is changed, update #in textarea outText.addEventListener('input', function() { inText = atob(outText); }); }); ```