A simple function to get the CSS style path of an element.

cssPath.js

const cssPath = (function () {
    function tagUnique(l) {
        const es = [].filter.call(
            l.parentElement.children,
            e => e !== l
        );
        return -1 === []
        .map.call(es, e => e.tagName)
        .indexOf(l.tagName);
    }
    function classUnique(l, tag) {
        const es = [].filter.call(
            l.parentElement.children,
            e => e !== l && !(
                tag === true &&
                e.tagName !== l.tagName
            )
        );
        return -1 === []
        .map.call(es, e => e.className)
        .filter(c => c !== '')
        .map(c => '.' + c.trim().replace(/\s+/g, '.'))
        .indexOf('.' + l.className.trim().replace(/\s+/g, '.'));
    }
    
    return el => {
        const names = [];

        while (el.parentNode) {
            if (el.id) {
                names.unshift('#' + el.id);
                break;
            }

            if (el == el.ownerDocument.documentElement) {
                names.unshift(el.tagName);
            }
            
            else if (el.className && classUnique(el, true)) {
                names.unshift(
                    (classUnique(el) ? '' : el.tagName) +
                    '.' + el.className.trim().replace(/\s+/g, '.')
                );
            }
            
            else if (tagUnique(el)) {
                names.unshift(el.tagName);
            }
            
            else {
                names.unshift(
                    el.tagName + ":nth-child(" +
                    ([].indexOf.call(
                        el.parentElement.children,
                        el
                    ) + 1) + ")"
                );
            }

            el = el.parentNode;
        }

        return names.join(" > ");
    };
})();