Select pager with javascript reload page

In Twig:

{% set limit = app.request.query.get('limit')|default(10) %}
<select class="form-control" onchange="pager()" id="perPageSelector">
    <option {% if limit == 10 %}selected{% endif %} value="10">10</option>
    <option {% if limit == 25 %}selected{% endif %} value="25">25</option>
    <option {% if limit == 50 %}selected{% endif %} value="50">50</option>
    <option {% if limit == 100 %}selected{% endif %} value="100">100</option>
</select>

In javascript:

function pager(val) {
    var pager = document.getElementById("log_search_type_limit"),
        perpage = pager.options[pager.selectedIndex].value,
        url = replaceQueryParam('limit', perpage, window.location.search);
    window.location = window.location.pathname + url;
}

function replaceQueryParam(param, newval, search) {
    var regex = new RegExp("([?;&])" + param + "[^&;]*[;&]?");
    var query = search.replace(regex, "$1").replace(/&$/, '');

    return (query.length > 2 ? query + "&" : "?") + (newval ? param + "=" + newval : '');
}