Hooking into WordPress AJAX actions

ajax-hooks.php

// if both logged in and not logged in users can send this AJAX request,
// add both of these actions, otherwise add only the appropriate one
add_action( 'wp_ajax_nopriv_myajax-submit', 'myajax_submit' );
add_action( 'wp_ajax_myajax-submit', 'myajax_submit' );

function myajax_submit() {
	// get the submitted parameters
	$postID = $_POST['postID'];

	// generate the response
	$response = json_encode( array( 'success' => true ) );

	// response output
	header( "Content-Type: application/json" );
	echo $response;

	// IMPORTANT: don't forget to "exit"
	exit;
}