const elementIsVisibleInViewport = (el, partiallyVisible = false) => { const { top, left, bottom, right } = el.getBoundingClientRect(); const { innerHeight, innerWidth } = window; return partiallyVisible ? ((top > 0 && top 0 && bottom 0 && left 0 && right = 0 && left >= 0 && bottom <= innerHeight && right <= innerWidth; }; // e.g. 100x100 viewport and a 10x10px element at position // {top: -1, left: 0, bottom: 9, right: 10} const top_header= document.querySelector('.top-header'); console.log(elementIsVisibleInViewport(top_header, true)); // true - (partially visible)