include checking for 0 and e in update qty methods

app/Cart.php

@@ -45,9 +45,11 @@ class Cart
 
     public function updateQty($product_id, $changed_qty)
     {
+        $changed_qty = abs($changed_qty);
+
         if (array_key_exists($product_id, $this->items)) {
-            if ($changed_qty <= 0) {
-                $this->removeItem($product_id);
+            if ($changed_qty === 0) {
+                $this->items[$product_id]['qty'] = 1;
             } else {
                 $this->items[$product_id]['qty'] = $changed_qty;
             }

public/js/cart.js

@@ -91,6 +91,12 @@ class Cart {
         function bindedUpdateItemQty(event) {
             if (!event.target.classList.contains('js-qty-input')) return;
 
+            const changedQty = event.target.value;
+            if (!changedQty || (changedQty.indexOf('e') + 1) || changedQty === '0') {
+                event.target.value = event.target.defaultValue;
+                return;
+            }
+
             const actionUrl = this.updateItemUrl;
             const productId = event.target.dataset.productId;