qsa2 = function(node, selector) {
    var selectors = selector.split(" ");
    var matches;
    var children;
    var child;
    var parents = node.getElementsByTagName(selectors[0]);
    if (parents.length > 0) {
        for (var i = 0; i < parents.length; i++) {
            children = parents[i].getElementsByTagName(selectors[1]);
            if (children.length > 0) {
                for (var i = 0; i < parents.length; i++) {
                    child = children[i];
                    matches.push(child); // somehow store our result here
                }
            }
        }
    }
    return matches;
  }

function qsa2(selector) {
    var next = document;
    selector.split(/s+/g).forEach(function(sel) {
        var arr = [];
        (Array.isArray(next) ? next : [next]).forEach(function(el) {
            arr = arr.concat( [].slice.call(el.getElementsByTagName(sel) ));
        });
        next = arr;
    });
    return next;
}

if (parents.length > 0) {
    for (var i = 0; i < parents.length; i++) {
        children = parents[i].getElementsByTagName(selectors[1]);
        if (children.length > 0) {
            for (var i = 0; i < parents.length; i++) { // <-----------------------

for (var i = 0; i < parents.length; i++) {
    children = parents[i].getElementsByTagName(selectors[1]);
        for (var k = 0; k < children.length; i++) {

var matches = [];
function recursivelySelectChildren(selectors, nodes){
    if (selectors.length != 0){
        for (var i = 0; i < nodes.length; i++){
            recursivelySelectChildren(nodes[i].getElementsByTagName(selectors[0]), selectors.slice(1))
        }
    } else {
        matches.push(nodes);
    }
}
function qsa(selector, node){
    node = node || document;
    recursivelySelectChildren(selector.split(" "), [node]);
    return matches;
}