So all jQuery's :visible
selector does is check the display property.
If that's all you want, this is all you'd need.
(window.getComputedStyle(el).getPropertyValue('display') !== 'none')
However, this is lacking in many use cases. If you seek a more comprehensive solution, keep reading.
Both Element.getBoundingClientRect() and window.getComputedStyle() are useful for determining if the element is visible and in the viewport.
You can't use getBoundingRect() alone to determine the visibility, and while you could use getComputedStyle() solely, it's not the optimal solution in terms of performance.
Both of these functions used in conjunction with each other is the best option (around 22% faster than getComputedStyle() alone.
function inViewport(els) {
let matches = [],
elCt = els.length;
for (let i=0; i<elCt; ++i) {
let el = els[i],
b = el.getBoundingClientRect(), c;
if (b.width > 0 && b.height > 0 &&
b.left+b.width > 0 && b.right-b.width < window.outerWidth &&
b.top+b.height > 0 && b.bottom-b.width < window.outerHeight &&
(c = window.getComputedStyle(el)) &&
c.getPropertyValue('visibility') === 'visible' &&
c.getPropertyValue('opacity') !== 'none') {
matches.push(el);
}
}
return matches;
}
With a usage example of...
var els = document.querySelectorAll('.one'),
visibleEls = inViewport(els);
This ensures that the display is not set to "none", the visibility is "visible", the width and height are greater than 0, and the element is within the bounds of the viewport.