Make post request without page reload in php

<?php
    $dates = array
    (
        '0' => "2013-02-18 05:14:54",
        '1' => "2013-02-12 01:44:03",
        '2' => "2013-02-05 16:25:07",
        '3' => "2013-01-29 02:00:15",
        '4' => "2013-01-27 18:33:45"
    );

    function closest($dates, $findate)
    {
        $newDates = array();

        foreach($dates as $date)
        {
            $newDates[] = strtotime($date);
        }

        echo "<pre>";
        print_r($newDates);
        echo "</pre>";

        sort($newDates);
        foreach ($newDates as $a)
        {
            if ($a >= strtotime($findate))
                return $a;
        }
        return end($newDates);
    }

    $values = closest($dates, date('2013-02-04 14:11:16'));
    echo date('Y-m-d h:i:s', $values);
?>

// in css:
/* Display line under clicked navbar link */
.active {
  text-decoration-line: underline !important;
  text-decoration-thickness: 2px !important;
  color: rgb(20, 19, 19);
}

//in html: 
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

    <script>
      $(document).ready(function () {
        // Underline to remain in navbar after click using URL
        jQuery(function ($) {
          var path = window.location.href; // because the 'href' property of the DOM element is the absolute path
          $('.nav-link').each(function () {
            if (this.href === path) {
              $(this).addClass('active');
            }
          });
        });
      });
    </script>

//Note class in link should be nav-link

//// Validate if Email field is spam
add_action( 'elementor_pro/forms/validation/email', function( $field, $record, $ajax_handler ) {
    // Looking if email found in spam array, you can add to the array
  $spamemails = array("ericjonesonline@outlook.com", "eric@talkwithwebvisitor.com");
    if ( in_array( $field['value'] , $spamemails) ) {
        $ajax_handler->add_error( $field['id'], 'אנחנו לא אוהבים ספאם, נסו מייל אחר' );
    }
}, 10, 3 );

$.ajax({
  type: "POST",
  url: url,
  data: data,
  success: success,
  dataType: dataType
});

var allElements = $("*");

<?php 
function count_num_finger( $n ) 
{ 
	$r = $n % 8; 
	if ($r == 1) 
		return $r; 
	if ($r == 5) 
		return $r; 
	if ($r == 0 or $r == 2) 
		return 2; 
	if ($r == 3 or $r == 7) 
		return 3; 
	if ($r == 4 or $r == 6) 
		return 4; 
}	 

// Driver Code 
$n = 30; 
echo(count_num_finger($n)); 
 
?> 

<?php 
// PHP program to find nth 
// magic number 

// Function to find nth 
// magic number 
function nthMagicNo($n) 
{ 
	$pow = 1; 
	$answer = 0; 

	// Go through every bit of n 
	while ($n) 
	{ 
	$pow = $pow * 5; 

	// If last bit of n is set 
	if ($n & 1) 
		$answer += $pow; 

	// proceed to next bit 
	$n >>= 1; // or $n = $n/2 
	} 
	return $answer; 
} 

// Driver Code 
$n = 5; 
echo "nth magic number is ", 
	nthMagicNo($n), "\n"; 

// This code is contributed by Ajit. 
?> 

add_filter( 'woocommerce_available_payment_gateways', 'conditionally_disable_cod_payment_method', 10, 1);
function conditionally_disable_cod_payment_method( $gateways ){
    // HERE define your Products IDs
    $products_ids = array(2880);

    // Loop through cart items
    foreach ( WC()->cart->get_cart() as $cart_item ){
        // Compatibility with WC 3+
        $product_id = version_compare( WC_VERSION, '3.0', '<' ) ? $cart_item['data']->id : $cart_item['data']->get_id();
        if (in_array( $cart_item['product_id'], $products_ids ) ){
            unset($gateways['cod']);
            break; // As "COD" is removed we stop the loop
        }
    }
    return $gateways;
}

use App\Http\Controllers\OtherController;

class TestController extends Controller
{
    public function index()
    {
        //Calling a method that is from the OtherController
        $result = (new OtherController)->method();
    }
}

2) Second way

app('App\Http\Controllers\OtherController')->method();

Both way you can get another controller function.

add_filter( 'woocommerce_product_get_stock_quantity' ,'custom_get_stock_quantity', 10, 2 );
add_filter( 'woocommerce_product_variation_get_stock_quantity' ,'custom_get_stock_quantity', 10, 2 );
function custom_get_stock_quantity( $value, $product ) {
    $value = 15; // <== Just for testing
    return $value;
}

//*****---  Remove Eicons:  ---*****
//==========================
add_action( 'wp_enqueue_scripts', 'remove_default_stylesheet', 20 ); 
function remove_default_stylesheet() { 
	wp_deregister_style( 'elementor-icons' ); 
}

$('iframe').attr('src', $('iframe').attr('src'));

// Replace source
$('img').on("error", function() {
  $(this).attr('src', '/images/missing.png');
});

// Or, hide them
$("img").on("error", function() {
  $(this).hide();
});

jQuery.extend({

  getQueryParameters : function(str) {
	  return (str || document.location.search).replace(/(^\?)/,'').split("&").map(function(n){return n = n.split("="),this[n[0]] = n[1],this}.bind({}))[0];
  }

});