javascriptCHeck if DOM element is visible in current viewport

var el = document.querySelector('div');
var rect = el.getBoundingClientRect();
var is_visible = rect.top >= 0 && rect.left >= 0 &&
                 rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
                 rect.right <= (window.innerWidth || document.documentElement.clientWidth);ctrl + c
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