Code Snippet Causing Multiple Ajax Calls – Flickering Images in WooCommerce cart

Hello,

There is an issue that presents itself as someone updates their zip code on the cart page to calculate shipping costs.

I have a CSV with 41K Zip Codes, Each Zip Code has 4 variables that affect pricing: S1, S2, S3, & N. Each Product has a weight (W).

the formula to calculate shipping cost is $ Zip Code Shipping Price = (S1*(W^n))+(S2*W)+S3

the following code calculates the shipping price following the above formula:

add_filter( 'woocommerce_shipping_calculator_enable_country', '__return_false' );
add_filter( 'woocommerce_shipping_calculator_enable_city', '__return_false' );
add_filter( 'woocommerce_shipping_calculator_enable_state', '__return_false' );

function my_custom_shipping_calculator_field() {
	global $wpdb, $session;
    if ( ! session_id() ) {
        session_start();
    }
	
	$zip_code = $_REQUEST['calc_shipping_postcode'];
	$_SESSION['zip_code_number'] = $zip_code;
	$wpdb_prefix = $wpdb->prefix;
	$wpdb_tablename = $wpdb_prefix.'prices_shipping';
	$result = $wpdb->get_results("SELECT * FROM $wpdb_tablename WHERE zip_code = '$zip_code' LIMIT 1");
	$s1 = $s2 = $s3 = $n = 0;
	foreach($result as $item){
		$s1 = $item->s1;
		$s2 = $item->s2;
		$s3 = $item->s3;
		$n = $item->n;
	}

	
	$sum_weight_shipping = 0;
    global $woocommerce;
	$item_cart = $woocommerce->cart->get_cart();
	foreach($item_cart as $item => $value){
		$product_item = wc_get_product($value["data"]->get_id());
		$product_item_weight =(float)$value["data"]->get_weight();
		$product_item_quantity = (int)$value['quantity'];

		$weight_shipping = $product_item_weight*$product_item_quantity;
		$sum_weight_shipping = $sum_weight_shipping + $weight_shipping;
	}

	$item_price_shipping = ($s1*pow($sum_weight_shipping,$n)) + ($s2*$sum_weight_shipping) + $s3;
	
	add_action( 'woocommerce_cart_calculate_fees', function($cart) use($item_price_shipping){
		WC()->cart->add_fee( __( 'Shipping Price', 'shipping_price' ) , $item_price_shipping , true);
	});
	
	if($item_price_shipping != 0){
		$_SESSION['item_price_shipping'] = $item_price_shipping;
		
	}
	
	if($zip_code != ""){
		WC()->customer->set_shipping_postcode(wc_clean($zip_code));
		WC()->customer->set_billing_postcode(wc_clean($zip_code)); 
	}
}
add_action( 'woocommerce_calculated_shipping', 'my_custom_shipping_calculator_field' );

/*	add_action('woocommerce_checkout_create_order', function($order, $data){
		$item_price_shipping = 50;
		$item_fee = new WC_Order_Item_Fee();
		$item_fee->set_name('Shipping Price');
		$item_fee->set_amount($item_price_shipping);
		$item_fee->set_tax_class('');
		$item_fee->set_tax_status('none');
		$item_fee->set_total($item_price_shipping);
		
		$order->add_item($item_fee);
		$order->calculate_totals();
		$order->save();
	});*/

/*
*/

add_action('woocommerce_before_checkout_form', 'custom_checkout_calculated_shipping', 1);
function custom_checkout_calculated_shipping() {
	global $session;
    if ( ! session_id() ) {
        session_start();
    }
    $zip_code_shipping = WC()->customer->get_shipping_postcode();
	$zip_code_billing = WC()->customer->get_postcode();
	$price_shipping = $_SESSION['item_price_shipping'];
	$zip_code = $_SESSION['zip_code_number'];
	
	if(($zip_code_shipping == "" && $zip_code_billing == "" && $zip_code == "") &&  !isset($price_shipping)){
		wp_redirect("/cart");
		$_SESSION["zip_code"] = false;
	}else{
		$_SESSION["zip_code"] = true;
	}
}

add_action( 'woocommerce_cart_calculate_fees', 'prefix_add_discount_line');
function prefix_add_discount_line( $cart ) {
	global $session;
    if ( ! session_id() ) {
        session_start();
    }
  if(isset($_SESSION['item_price_shipping'])){
	   $item_price_shipping = $_SESSION['item_price_shipping'];
  }else{
	  $item_price_shipping = 0;
  }	
 
  $cart->add_fee( __( 'Shipping Price', 'shipping_price' ) , $item_price_shipping );
}

add_action('woocommerce_before_cart_contents', 'zip_code_not_found_message');
function zip_code_not_found_message() {
 	global $session;
    if ( ! session_id() ) {
        session_start();
    }
	if($_SESSION["zip_code"] == false){
		    $message='<div class="zip_code_not_found_message">';
				$message.='<h2>Shipping Zip code is required</h2>';
				$message.='<p align="justify">Please enter your zip code.</p>';
			$message.='</div>';
		    echo $message;
	}
	
}

function js_code_shipping() {
    ?>
    <script type="text/javascript">
       jQuery(document).ready(function($){
		   $( document.body ).on( 'updated_cart_totals', function(){
				$("button[name='calc_shipping']").click();
		   });
		   $( document.body ).on( 'added_to_cart', function(){
                $("button[name='calc_shipping']").click();
           });
		   
		   const text_shipping = $(".woocommerce-shipping-destination strong").text().replace("OH","Zipcode:");
		   $(".woocommerce-shipping-destination strong").text(text_shipping);
		   $(".woocommerce-shipping-destination strong").css("display","inline-block");
	   });
		
    </script>
    <?php
}
add_action( 'wp_footer', 'js_code_shipping' );

this code snippet causes the page to continuously make a call via ajax after the zipcode is input:

here is what happens in the console:

any advice on how to fix this? this is presenting on multiple browsers and devices.

thank you in advance!

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