document.querySelectorAll('.outer').forEach(el => { let content = el.querySelector('.content'); repeatContent(content, el.offsetWidth); let slider = el.querySelector('.loop'); slider.innerHTML = slider.innerHTML + slider.innerHTML; }); function repeatContent(el, till) { let html = el.innerHTML; let counter = 0; // prevents infinite loop while (el.offsetWidth < till && counter < 100) { el.innerHTML += html; counter += 1; } }