pass on url parameters: append all url parameters from the visited page to every anchor tag in that page

pass_on_url_parameters.js

<script>
    var getParams = function (url) {
        var params = {};
        var parser = document.createElement('a');
        parser.href = url;
        var query = parser.search.substring(1);
        var vars = query.split('&');
        for (var i = 0; i < vars.length; i++) {
            var pair = vars[i].split('=');
            if (typeof (pair[1]) !== 'undefined') {
                params[pair[0]] = decodeURIComponent(pair[1]);
            }
        }
        return params;
    };
    var encodeQueryData = function (data) {
        const ret = [];
        for (let d in data)
            ret.push(encodeURIComponent(d) + '=' + encodeURIComponent(data[d]));
        return ret.join('&');
    }
    let visit_params = getParams(window.location.href);
    let links = document.getElementsByTagName('a');

    function what_j(u) {
        let joiner = ''
        if (u.indexOf('?') === -1) {
            joiner = '?'
        } else {
            joiner = '&'
        }
        return joiner;
    }

    for (var i = 0; i < links.length; i++) {
        let joiner = what_j(links[i].href);
        let encoded_params = encodeQueryData(visit_params);
        if (encoded_params.length > 0) {
            links[i].href = links[i].href + joiner + encoded_params
        }
    }
</script>