JSFiddle - React, Tailwind, and code Playground

HTML

<td id="check-box"><input type="checkbox" name="checkbox"></td>
<td id="qty-box"><input type="text" name="qtybox"></td>

<script type="text/javascript">    
    $(document).ready(function()
    {
        $("input[name='checkbox']").click(function()
        {
            if($(this).is(':checked'))
            { 
                $("input[name='qtybox']").val("1");
            }
            else
            {
                $("input[name='qtybox']").val("");
            }
        });
    });
</script>