XPATH in the browser

xPath.js

function Elem2Xpath(elt) {
    function getElementIdx(elt) {
        let count = 1;
        for (let sib = elt.previousSibling; sib; sib = sib.previousSibling) {
            if (sib.nodeType == 1 && sib.tagName == elt.tagName)
                count++
        }

        return count;
    }
    let path = "";
    for (; elt && elt.nodeType == 1; elt = elt.parentNode) {
        idx = getElementIdx(elt);
        xname = elt.tagName;
        if (idx > 1)
            xname += "[" + idx + "]";
        path = "/" + xname + path;
    }
    return path;
}

function Xpath2Elem(xpath) {
    return document.evaluate(
        xpath, 
        document, 
        null, 
        XPathResult.FIRST_ORDERED_NODE_TYPE, 
        null
    ).singleNodeValue
}