lickybuay

I know it’s not the best way, but made it work like this:

JS

document.querySelector('.age-gate__submit--yes').addEventListener('click', async (e) => {
const header = {
'accept': 'application/json',
'content-type': 'application/json',
'Access-Control-Allow-Origin': '*'
};
const email = document.getElementsByClassName("age-email-input")[0].value;
const endpointUrl = https://yoursite.com/wp-json/yoursite/age-gate-email;
const rawResponse = fetch(endpointUrl, {
method: 'POST',
headers: header,
body: JSON.stringify({email: email })
});
});

Theme Function.php

function ageGateAddUser( WP_REST_Request $request ) {	
	$parameters = $request->get_json_params();
	$email = $parameters['email'];
	if($email!=""){
	//Do whatever you need here
	}	
	return new WP_REST_Response($email);
}

 add_action( 'rest_api_init', function () {
	register_rest_route( 'yoursite', 'age-gate-email', array(
	  'methods' => 'POST',
	  'callback' => 'ageGateAddUser',
	));
});