JSFiddle - React, Tailwind, and code Playground

HTML

<div id="fp_parameters_list">
    <div data-parameter-id="3"></div>
    <div data-parameter-id="2"></div>
    <div data-parameter-id="10" style="display:none"></div>
    <div data-parameter-id="1"></div>
</div>

JavaScript

function mySort(){ // Do not pass hidden clones
    var items = [];
    $('#fp_parameters_list').children().each(function(){
        if ($(this).is(':visible')) {         
            items.push($(this).attr('data-parameter-id'));
        }
    });
    return items;
}

// This gives correct ordering
$.ajax({
    url: '/echo/json/',
    type: 'post',
    dataType: 'json',
    data: {
        ordering: mySort()
    }
});


// This gives ordering as a string
$.ajax({
    url: '/echo/json/',
    type: 'post',
    dataType: 'json',
    data: {
        ordering: function mySort(){ // Do not pass hidden clones
            var items = [];
            $('#fp_parameters_list').children().each(function(){
                if ($(this).is(':visible')) {         
                    items.push($(this).attr('data-parameter-id'));
                }
            });
            return items;
        }
    }
});