retrieve a CSS selector out of a DOM node

document.retrieveSelector.js

document.retrieveSelector = (function (filter) {

    // (C) WebReflection - Mit Style License

    function elementsOnly(element) {
        return element.nodeType == 1;
    }

    function createSelector(element, documentElement, path, first) {
        var
            nodeName = element.nodeName,
            parentNode = element.parentNode
        ;
        switch (true) {
            case !!element.id:
                path.push("#" + element.id);
                break;
            case first:
                first = !first;
                nodeName += ":nth-child(" + (
                    1 + filter.call(parentNode.childNodes, elementsOnly).indexOf(element)
                ) + ")";
            case element != documentElement:
                createSelector(parentNode, documentElement, path);
            default:
                path.push(nodeName);
                break;
        }
        return path;
    }
    // partial polyfill for this code purpose only
    filter || (filter = function () {
        function indexOf(o) { // node always unique
            for (var i = this.length; i-- && this[i] !== o;);
            return i;
        }
        return function (fn) {
            for (var r = [], i = 0, length = this.length; i < length; i++) {
                fn(this[i]) && r.push(this[i]);
            }
            r.indexOf = indexOf;
            return r;
        };
    }());

    return function retrieveSelector(element) {
        var ownerDocument = element.ownerDocument;
        return ownerDocument ? createSelector(
            element.nodeType != 1 ? element.parentNode : element,
            ownerDocument.documentElement,
            [],
            true
        ).join(">") : "";
    };

}([].filter));