JSFiddle - React, Tailwind, and code Playground

HTML

<table class="sku_table" id="order_line_1">
    <tbody>
        <tr>
            <td>Item Code</td>
            <td class="heading">UOM</td>
            <td class="heading">Quantity</td>
        </tr>
        <tr>
            <td>
                <select class="sku_dropdown" name="sku_dropdown">
                    <option value="empty">Select Item</option>
                    <option value="afd433" selected>afd433</option>
                    <option value="afd434">afd434</option>
                    <option value="afd435">afd435</option>
                    <option value="afd436">afd436</option>
                </select>
            </td>
            <td>
                <select class="hidden sku_uom_dropdown sku_uom_dropdown_BN-HOSAF-D" name="sku_uom_dropdown">
                    <option value="DR">DR</option>
                    <option value="PL">PL</option>
                </select>
                <select class="sku_uom_dropdown sku_uom_dropdown_L001S999 hidden" name="sku_uom_dropdown">
                    <option value="DR">DR</option>
                    <option value="PL">PL</option>
                </select>
                <select class="hidden sku_uom_dropdown sku_uom_dropdown_L002S994" name="sku_uom_dropdown">
                    <option value="CS">CS</option>
                    <option value="PL">PL</option>
                </select>
                <select class="sku_uom_dropdown sku_uom_dropdown_L005S985" name="sku_uom_dropdown">
                    <option value="CS">CS</option>
                    <option value="PL">PL</option>
                </select>
            </td>
            <td class="sku_qty">
                <input type="text" name="quantity" class="sku_qty">
            </td>
        </tr>
    </tbody>
</table> <a href='#' id='submit'>PROCESS</a>

<div id='result'></div>

CSS

.hidden {display:none}

JavaScript

$("#submit").click(function () {

    var data = {};
    
    $(".sku_table input, .sku_table select").not('.hidden').each(function () {
        var id = $(this).closest('.sku_table').attr("id");
        var name = $(this).attr("name");
        var val = $(this).val();
        
        if (name == 'sku_dropdown' && val == 'empty') {
            $(this).find("option:second").attr("selected", true);
            var val = $(this).find("option:second").val();
        }
        
        if (name == 'sku_uom_dropdown' && val == '') {
            $(this).find("option:first").attr("selected", true);
            var val = $(this).find("option:first").val();
        }
        
        if (name == 'quantity' && val == '') {
            var val = '0';
        }
        
        alert(name+" = "+val);
        
        data[id] = [name];
        data[id][name] = val;
    });

    var json = JSON.stringify(data);

    $("#result").html(json);

});