Basic AJAX request set up

ajax-handle.php

<?php

class CT_Config_Ajax{

	function __construct(){
		add_action( 'wp_ajax_ct_get_sku', array( $this, 'get_sku' ) );
		add_action( 'wp_ajax_nopriv_ct_get_sku', array( $this, 'get_sku' ) );
	} // __construct

	public function get_sku(){
		check_ajax_referer( 'ct_configurator_nonce', 'security' );

		wp_send_json_success( 'something' );
	} // get_sku

} // CT_Config_Ajax

new CT_Config_Ajax();


		wp_enqueue_script('script_slug', plugins_url( '/$plugin_folder/js/ct-configurator-frontend-scripts.min.js' ), array('jquery'), '1.0', true);
		wp_localize_script( 'script_slug', 'CTConfig', array(
			'ajaxurl'               => admin_url( 'admin-ajax.php' ),
			'ct_configurator_nonce' => wp_create_nonce( 'ct_configurator_nonce' ),
		) );

ajax.js

				var data = {
					action: 'ct_get_sku',
					product_id: selected_product_id,
					security: CTConfig.ct_configurator_nonce
				};

				$.post( CTConfig.ajaxurl, data, function( response ) {
					console.log(response);

					if ( response.success === true ){
						// deal with true
					}

					if ( response.success === false ){
						// deal with false
					}
				});