How to send 'alert' from controller in json?

Question

I am currently trying to stop redirecting to product view page if someone forgets to select configure option and click on 'add to cart', instead of that it will just send popup message or alert.

Here is the Controller:

File Name: Add.php

File Path:

Magento\Checkout\Controller\Cart\Add

protected function goBack($backUrl = null, $product = null)
{ 
 $result = [];
 if ($backUrl || $backUrl = $this->getBackUrl()) {
 $backUrlas = "test";
 $result['backUrl'] = $backUrlas;
 } else {
 //some code
 }
 $this->getResponse()->representJson(
 $this->_objectManager->get(\Magento\Framework\Json\Helper\Data::class)->jsonEncode($result)
 );
}

as you can see if I pass value "test" it will redirect to ../test instead of that ../product.

I am not good in json, any help would be appreciated!

Answer 1

Add like below and check

protected function goBack($backUrl = null, $product = null)
{ 
 $result = [];
 if ($backUrl || $backUrl = $this->getBackUrl()) {
 $result['backUrlas'] = "Test";
 $result['backUrl'] = $backUrl;
 } else {
 //some code
 }
 $this->getResponse()->representJson(
 $this->_objectManager->get(\Magento\Framework\Json\Helper\Data::class)->jsonEncode($result)
 );
}