WooCommerce additional custom popup on checkout when processing payment

functions.php

add_action( 'woocommerce_before_checkout_form', 'custom_payment_overlay' );
function custom_payment_overlay(){
	echo sprintf('<div class="custom-payment-popup"><div class="wpt-payment-overlay"></div><div class="wpt-payment-message">%s</div></div>',
		'We are processing your payment. Please hold on and do not refresh your browser.'
	);
}

script.js

// Display popup when form submitted
var checkout_form = $( 'form.checkout' );

checkout_form.on( 'checkout_place_order', function() {
    $(".custom-payment-popup").show();
		return true;
});

// Hide popup if form returns an error
$( document.body ).on( 'checkout_error', function() {
		$(".custom-payment-popup").hide();
});