Why is the js file being loaded twice?

Question

JavaScript

Hello!

There is a website on codeigniter with a table whose rows are broken by paganization. There is also row sorting, which works via ajax (the request leaves, the response rewrites the table and pagination buttons). Transition through the pages is also on ajax, the handler for clicking on the pagination button weighs.
On the first click, it sends a request and, on response, overwrites the table, and for some reason loads a js script that processes all ajax. In the browser console, it looks like this:

On the second click:

the handler fires twice, and so exponentially.
Here is the script that sends ajax:

"use strict";

var SortGroup = {
    onReady: function () {

        $('.btn-sort').on("click", function () {
            SortGroup.updTable(this);
        });

        $(document).on("click", ".ajax a", function (event) {
            event.preventDefault();
            SortGroup.nextPage(this);
            // alert(this);
        });
    },

    updTable: function (btn) {
        var arr_fld = {'Username': 'username', 'E-mail': 'e_mail', 'Date': 'created_date'};
        var arr_tp = {'/\\': 'DESC', '\\/': 'ASC'};
        var fld = $(btn).text().split(' ')[0];
        var tp = $(btn).text().split(' ')[1];
        var url = "http://guestbook.local/index.php/homepage/ajax_table";
        var data = {
            field: arr_fld[fld],
            type: arr_tp[tp]
        };
        var jqxht = $.post(url, data, function (data) {
            $('.entries-block').html(data);
            $(btn).text(fld + " " + tp.split("").reverse().join(""));
        });
        jqxht.fail(function () {
            alert('Reload page and try again');
        });
    },

    nextPage: function (ref) {
        var url = ref;
        var jqxht = $.post(url, {}, function (data) {
            $('.entries-block').html(data);
        });
        jqxht.fail(function () {
            alert('Reload page and try again');
        });
    }
};

$(document).ready(SortGroup.onReady());

How to solve the problem with the increasing number of requests?

UPD: I looked with the VisualEvent plugin, after loading the table page using the pagination buttons, one more load event is hung on the buttons, even if you unsubscribe from these events using .off();

UPD2:
Initial loading

Update via ajax, which SortGroup.nextPage (this);

Answer 1

it is good practice to unsubscribe (.off) from events by resubscribing (.on) to them so that there are no such problems.

$('.btn-sort')
            .off('click.updateTable')
            .on('click.updateTable', fn ());

Answer 2

If you work under Chrome, install the VisualEvent plugin and see how events are hung.