Check out example codes for "bootstrap dropright overflow issue". It will help you in understanding the concepts better.

Code Example 1

$(document).on('show.bs.dropdown', '.scrolled-heighted-box', function(e) {
        var dropdown = $(e.target).find('.dropdown-menu');

            dropdown.appendTo('body');
        $(this).on('hidden.bs.dropdown', function () {
            dropdown.appendTo(e.target);
        })
    });

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