WP Admin AJAX Call

script.js

const item = {
  action: 'custom_add_to_cart',
  product_id: Button.getAttribute( 'data-product_id' ),
  quantity: document.querySelector( '.qty[name="quantity"]' ).value
};

var formData = new FormData();
for ( let key in item ) {
  formData.append( key, item[key] );
}

var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function () {
  if ( xhr.readyState === 4 && xhr.status === 200 ) {
    let response = JSON.parse( xhr.responseText );

    if ( response.success ) {
      window.location.replace( response.data.cart_url );
    } else {
      alert( response.data );
    }
  }
}

// xhr.open( 'POST', "<?php echo admin_url( 'admin-ajax.php' ); ?>", false );
xhr.open( 'POST', wc_add_to_cart_params.ajax_url, false );
xhr.send( formData );

scripts.js

// JS Code
$( '.button' ).on( 'click', function ( event ) {
  var data = {
    action: 'action_name'
  };
		
  $.post( lf_ajax.ajax_url, data, function ( response ) {
    console.log( response );
  } );
} );


// PHP Code
function lf_add_cookies_ip() {
  // code here...
  
  die();
}

add_action( 'wp_ajax_lf_cookies_ip', 'lf_add_cookies_ip' );
add_action( 'wp_ajax_nopriv_lf_cookies_ip', 'lf_add_cookies_ip' );

vanilla.js

document.querySelector( '#btn' ).addEventListener( 'click', function ( event ) {
  event.preventDefault();

  let formData = new FormData();
  formData.append( 'action', 'hand_dryers_filters' );
  
  let xhr = new XMLHttpRequest();
  xhr.onreadystatechange = function () {
    if ( this.readyState == 4 && this.status == 200 ) {
      let response = JSON.parse( this.responseText );
      
      console.log( response );
      
      if ( response.success ) {
        window.location.replace( response.data.cart_url );
      } else {
        alert( response.data );
      }
    }
  };
  xhr.open( "POST", "<?php echo admin_url( 'admin-ajax.php' ); ?>", false );
  xhr.send( formData );
} );