Run ajax in certain time interval in Magento2

This may be form key issue.In ajaxDeleteAction() function,magento is check form key using below code:

   if (!$this->_validateFormKey()) {
        Mage::throwException('Invalid form key');
    }

Create layout XML

/app/code/Company/Module/view/frontend/layout/module_index_custom.xml

<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
    <referenceContainer name="content">
        <block class="Company\Module\Block\Custom" name="customer_index_gallery" template="Vendor_Module::custom.phtml" cacheable="false"/>
    </referenceContainer>
</page>

/app/code/Company/Module/Block/Custom.php

<?php

namespace Vendor\Module\Block;

class Custom extends \Magento\Framework\View\Element\Template
{
    /**
     * Construct
     *
     * @param \Magento\Framework\View\Element\Template\Context $context
     * @param array $data
     */
    public function __construct(
        \Magento\Backend\Block\Template\Context $context,
        array $data = []
    )
    {
        parent::__construct($context, $data);
       }

    /**
     * Get form action URL for POST booking request
     *
     * @return string
     */
    public function getFormAction()
    {
        return '/companymodule/controller_name/custom';
        // here controller_name is index, action is booking
    }
}

/app/code/Company/Module/view/frontend/templates/custom.phtml

<form action="<?php echo $block->getFormAction() ?>" method="post">
    <input name="firstname" type="text">
    <input name="lastname" type="text">
    <input name="email" type="text">
    <input type="submit" value="informations">
</form>

/app/code/Company/Module/Controller/Index/Custom.php

<?php

namespace Company\Module\Controller\Index;

use Magento\Framework\Controller\ResultFactory;

class Custom extends \Magento\Framework\App\Action\Action
{
    /**
     * Booking action
     *
     * @return void
     */
    public function execute()
    {
        // 1. POST request : Get booking data
        $post = (array) $this->getRequest()->getPost();

        if (!empty($post)) {
            // Retrieve your form data
            $firstname   = $post['firstname'];
            $lastname    = $post['lastname'];
            $email       = $post['email'];
          
            // Doing-something with...

            // Display the succes form validation message
            $this->messageManager->addSuccessMessage('Booking done !');

            // Redirect to your form page (or anywhere you want...)
            $resultRedirect = $this->resultFactory->create(ResultFactory::TYPE_REDIRECT);
            $resultRedirect->setUrl('/companymodule/index/custom');

            return $resultRedirect;
        }
  
    }
}