Find all elements on a page with a specified z-index and log them to the console, sorted high to low

zindex.js

'use strict';
(function() {

    var allElements = document.querySelectorAll('*');

    var zIndexElements = [].map.call(allElements, function(el) {
        var style = window.getComputedStyle(el, null);
        var zIndex = style.getPropertyValue('z-index');

        return {
            el: el,
            zIndex: zIndex && zIndex !== 'auto' ? parseInt(zIndex) : undefined
        }
    })
        .filter(el => el.zIndex)
        .sort((a, b) => {
            return b.zIndex - a.zIndex;
        });

    console.table(zIndexElements);

})();