var args = [
    {
        domain: /^(.*\.)?facebook\.com$/,
        args: ['__tn__', '__xts__[0]']
    }, {
        domain: /^(.*\.)?instagram\.com$/,
        args: ['igshid']
    }, {
        domain: /^(.*\.)?youtube\.com$/,
        args: ['feature']
    }, {
        domain: /^(.*\.)?repubblica\.it$/,
        args: ['ref']
    }, {
        domain: /./,
        args: ['fbclid', 'gclid',
            'utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
            'refresh_ce']
    }
];

function sanitizeUrl(node, url, list) {
    var changed;

    for (var i = 0; i < list.length; i++) {
        if (url.searchParams.has(list[i])) {
            changed = true;
            url.searchParams.delete(list[i]);
        }
    }

    if (changed)
        node.value = url.toString();
}

function sanitizeNode(node) {
    if (node.tagName != 'A')
        return;

    var href = node.attributes['href'];
    if (!href)
        return;

    href = href.value;
    url = new URL(href, location.origin);

    if (url.protocol != 'http:' && url.protocol != 'https:')
        return;

    for (var i = 0; i < args.length; i++)
        if (url.hostname.match(args[i].domain))
            sanitizeUrl(node.attributes['href'], url, args[i].args);
}

function walk(node) {
    // thanks to: http://is.gd/mwZp7E
    switch (node.nodeType) {
        case  1: // Node.ELEMENT_NODE
            sanitizeNode(node);
        case  9: // Node.DOCUMENT_NODE
        case 11: // Node.DOCUMENT_FRAGMENT_NODE
            var child = node.firstChild;
            while (child) {
                var next = child.nextSibling;
                walk(child);
                child = next;
            }
            break;
    }
}

// register a MutationObserver to handle DOM edits by client-side JS.
new MutationObserver(function (mlist) {
    for (var i = 0; i < mlist.length; i++)
        walk(mlist[i].target);
}).observe(document, {
    childList: true,
    subtree: true,
    attributes: true,
    attributeFilter: ['href'],
})

walk(document.body);