JSFiddle - React, Tailwind, and code Playground

HTML

<td>
  <div class="sp-quantity">
    <div class="container" style=" font-size:14px; ">
      <div class="sp-minus fff"> <a class="ddd" href="#">-</a>
      </div>
      <div class="sp-input">
        <input type="text" class="quantity-input" value="1">
      </div>
      <div class="sp-plus fff"> <a class="ddd" href="#">+</a>
      </div>
    </div>
</td>

JavaScript

$(".ddd").on("click", function() {
  alert('testing');

  var $button = $(this),
    $input = $button.closest('.sp-quantity').find("input.quantity-input");
  var oldValue = $input.val(),
    newVal;

  if ($.trim($button.text()) == "+") {

    newVal = parseFloat(oldValue) + 1;
  } else {
    // Don't allow decrementing below zero
    if (oldValue > 0) {
      newVal = parseFloat(oldValue) - 1;
    } else {
      newVal = 0;
    }
  }

  $input.val(newVal);
});