1. Create a new folder in the wp-content/plugins/ directory of your WordPress installation. Name it something relevant to your plugin, for example, my-tinymce-button-plugin.
2. Inside the plugin folder, create a PHP file (e.g., my-tinymce-button-plugin.php) and add the necessary plugin header information at the top of the file:

<?php  

/*

Plugin Name: My TinyMCE Button Plugin  

Description: Adds a custom TinyMCE button to the editor.

Version: 1.0  

Author: Your Name  

*/



// Plugin code will go here

3. Add the code to enqueue your JavaScript file with the TinyMCE button functionality. You can do this by hooking into the admin_enqueue_scripts action in WordPress:

function my_enqueue_tinymce_button_script() {

    wp_enqueue_script('my-tinymce-button-script', plugin_dir_url(__FILE__) . 'js/my-tinymce-button-script.js', array('jquery'), null, true);

}

add_action('admin_enqueue_scripts', 'my_enqueue_tinymce_button_script');

4. Now create the JavaScript file (my-tinymce-button-script.js) inside a js folder in your plugin directory. This file should contain the code to add your custom TinyMCE button:

(function() {

    tinymce.PluginManager.add('my_tinymce_button', function(editor, url) {

        editor.addButton('my_tinymce_button', {

            text: 'My Button',

            icon: false,

            onclick: function() {

                // Call the function in functions.php  

                // You can use ajax to send a request to your server and get the response      

                jQuery.post(ajaxurl, {

                    action: 'my_custom_tinymce_button_action'

                }, function(response) {

                    alert('Response: ' + response);

                });

            }

        });

    });

})();

5. In your functions.php file, create the function that will be called when the TinyMCE button is clicked:

function my_custom_tinymce_button_action() {

    // Your custom functionality here  

    echo 'Response from the custom function!';

    wp_die();

}

add_action('wp_ajax_my_custom_tinymce_button_action', 'my_custom_tinymce_button_action');