refactor
by Dmitry Morar
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="text" class="cat" value="1">
<button class="plus">+</button>
<button class="minus">-</button>
JavaScript
this.stepUpAmountInput = function() {
let inputAmount = $('.cat');
let quantity = parseInt(inputAmount.val(), 10);
let productUnit = 1;
inputAmount.val(quantity + productUnit);
};
this.stepDownAmountInput = function() {
let inputAmount = $(this.attr.inputAmount);
let quantity = parseInt(inputAmount.val(), 10);
let productUnit = 1;
if (quantity > productUnit) {
inputAmount.val(quantity - productUnit);
}
};