JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    цена<input type="text" name="price[]" class="priceA tc" value="300" readonly>
  кол-во<input type="text" name="kol[]" class="kolA tc" value="1" autocomplete="off"><div class="fav-pm" style="display:inline-block"><span class="fav-m left">-</span><span class="fav-p right">+</span></div>
  сумма<input type="text" name="stoim[]" class="stoimA tc" readonly>
</div>
------------------------
<div>
    цена<input type="text" name="price[]" class="priceA tc" value="299" readonly>
  кол-во<input type="text" name="kol[]" class="kolA tc" value="1" autocomplete="off"><div class="fav-pm" style="display:inline-block"><span class="fav-m left">-</span><span class="fav-p right">+</span></div>
  сумма<input type="text" name="stoim[]" class="stoimA tc" readonly>
</div>
------------------------
<p>Итог</p><input type="text" name="itog" class="itog" readonly>

JavaScript

jQuery(document).ready(function() {
  $.each($('.priceA'), function() {
    var priceA = $(".priceA", $(this).parent()).val(),
      kolA = $(".kolA", $(this).parent()).val(),
      stoimA = priceA * kolA;
    $(".stoimA", $(this).parent()).val(stoimA);
    $('.itog').val($('.itog').val() * 1 + stoimA);

  });

  $(".priceA, .kolA").on('input', function() {
    priceA = $(".priceA", $(this).parent()).val();
    kolA = $(".kolA", $(this).parent()).val();
    $(".stoimA", $(this).parent()).val(priceA * kolA);
    $('.itog').val(0);
  });
});

$(".fav-p").click(function(){
var i = $(this).parent().prev();
i.val(i.val() * 1 + 1);
});

$(".fav-m").click(function(){
var i = $(this).parent().prev();
i.val(i.val() * 1 - 1);
if (i.val()<1) i.val(1);
});