JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr>
        <td>
            <input name="checkbox[1]" type="checkbox" value="0" />
        </td>
        <td>
            <input name="items[1]" type="text" value="Forbiden Rice" />
        </td>
        <td>
            <input name="quantity[1]" type="text" value="1" />
        </td>
        <td>
            <select name="esquantity[1]" req="false">
                <option value="" selected>Choose Quantity</option>
                <option value="1">1</option>
            </select>
        </td>
    </tr>
    <tr>
        <td>
            <input name="checkbox[2]" type="checkbox" value="1" />
        </td>
        <td>
            <input name="items[2]" type="text" value="Organic Double White Rice " />
        </td>
        <td>
            <input name="quantity[2]" type="text" value="1" />
        </td>
        <td>
            <select name="esquantity[2]" req="false">
                <option value="" selected>Choose Quantity</option>
                <option value="1">1</option>
            </select>
        </td>
    </tr>
    <input type="submit" name="Submit" value="Submit" />
</table>

JavaScript

$(function () {
    $("input[name^='checkbox']").change(function () {
        var id = this.name.substring(8);
        if (this.checked) {
            $("[name='esquantity" + id + "']").attr("req", "true");
        } else {
            $("[name='esquantity" + id + "']").attr("req", "false");
        }

        //console.log($("[name='esquantity" + id + "']").attr("req"));
    });

    $("input[name='Submit']").click(function () {
        var i;
        for(i = 1; i <= parseInt($("[name^='esquantity']").length); i++) {
            if ($("[name='esquantity[" + i + "]']").attr("req") == "true" &&
                $("[name='esquantity[" + i + "]']").val() == "")
                alert("Please select a value for the required lists");
        }
    });
});