Magento 2 - Call Ajax controller on click of place order?

I've set up the JS, and controller and checkout.html

I need to call the controller with ajax to getPrice() method. My controller name is GetAjax.php and here is the controller code.

<?php

namespace Iostpay\Iostpaymagento\Controller\Index;

use Magento\Framework\Controller\ResultFactory;

class GetAjax extends \Magento\Framework\App\Action\Action
{
    public function __construct(
        Context  $context,
        \Magento\Framework\Controller\Result\JsonFactory $resultJsonFactory
    ) {
        $this->resultJsonFactory = $resultJsonFactory;
        parent::__construct($context);
    }

    public function execute()
    {
        print($this->getRequest()->getParam('customdata1'));
        print("heuss");
        die();
        /** @var \Magento\Framework\Controller\Result\Json $result */
        $result = $this->resultJsonFactory->create();

        return $result->setData(['success' => true]);
    }
}

And the JS code which triggers on click of place order.

require(["jquery"], function ($) {
    function transfer() {
        var customurl = "modulename/index/GetAjax'";
        $.ajax({
            url: customurl,
            type: 'POST',
            dataType: 'json',
            data: {
                customdata1: 'test1',
                customdata2: 'test2',
            },
            complete: function(response) {
                console.log( response );
            },
            error: function (xhr, status, errorThrown) {
                console.log('Error happens. Try again.');
            }
        });
   }
});

The Error I get in console is

POST http://127.0.0.1/magento3/newmodule/GetAjax/execute 404 (Not Found)

How can I execute any specific method from the controller.