WP_AJAX-create-post.php

<?php

Class CreatePost extends WP_AJAX
{
    protected $action = 'create_post';

    protected function run(){
        if($this->isLoggedIn()){
            $post = [
                'post_status' => 'publish'
            ];
            
            if( $this->requestType(['POST', 'put']) ){
                $post['post_content'] = 'This request was either POST or PUT';
            }else if( $this->requestType('get') ){
                $post['post_content'] = 'This request was GET';
            }

            $post['post_title'] = sprintf('This post was created by %s', $this->user->data->user_nicename);
            
            wp_insert_post($post);

            $this->JSONResponse($post);
        }
    }
}