JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.js"></script>
<div class="form-group stepper-type-1">
<input type="number" data-zeros="true" value="0" min="0" max="10" class="order_input_qnt" product_val="5">
</div>
<div class="form-group stepper-type-1">
<input type="number" data-zeros="true" value="0" min="0" max="10" class="order_input_qnt" product_val="4">
</div>
<div class="form-group stepper-type-1">
<input type="number" data-zeros="true" value="0" min="0" max="10" class="order_input_qnt" product_val="3">
</div>
<hr>
Val: <span class="order_total_price"></span>

JavaScript

jQuery(function ($)
{
  $('.order_input_qnt').on('change',function()
  {
      $(".order_total_price").html("...");
			
      var sum = 0;
      $(".order_input_qnt").each(function()
      {
      	 if ($(".order_input_qnt").val().length > 0) {
       		 var valor = parseFloat($(".order_input_qnt").attr("product_val")) * parseFloat($(".order_input_qnt").val());
       		 sum += valor;
         }
      });
      $(".order_total_price").html(sum.toFixed(2));

  });
});