Magento2 update cart on qty change event plugin created

Question

My website i have updatecart on qty btn change event call so with ajax how to created a plugin for this.

Answer 1

Vendor/Module/etc/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">    
    <type name="Magento\Checkout\Model\Cart">
        <plugin name="update_cart" type="Vendor\Module\Plugin\UpdateCart" sortOrder="999" disabled="false"  />
    </type>
</config>

Vendor\Module\Plugin\UpdateCart.php

<?php

namespace Vendor\Module\Plugin;

/**
 * Class afterUpdateItems
 * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
 */
class UpdateCart {

    public function afterUpdateItems($subject, $result, $data)
    {   
        foreach ($data as $itemId => $itemInfo) {
            $item = $subject->getQuote()->getItemById($itemId);
            $item->setQty(5);
        }        
        return $result;
    }
}