TinyMCE class editor Advanced Custom Formats / Styles / Shortcode Buttons including latex formular editor support #wordpress

editor-style.css

/* step 1: load this in editor-style.css in the theme folder */
/* step 2: activate function "Create CSS classes menu" in tinymce advanced settings */
/* step 3: add "Formate" to toolbar in tinymce advanced settings */
/* this gets shown automatically in the formats dropdown */
/* sometimes this is a little bit tricky. delete and recreate "Formats" in the Tinymce Advanced settings */
/* this also can be a programmable alternative: https://codex.wordpress.org/TinyMCE_Custom_Styles */
.Spezial-Button {
    background-color:red; 
    color:#fff;
    display: inline-block;
    text-decoration:none;
    padding:5px 10px;
    font-weight:bold;
    margin:0 5px;
}

/* if you want to add styles, but don't want them added to the menu, prefix them with .mceContentBody.wp-editor */
.mceContentBody.wp-editor .foo {
 	/* ... */ 
}

functions.php

<?php 
add_action('admin_head', function()
{
    // check user permissions
    if( !current_user_can('edit_posts') && !current_user_can('edit_pages') )
    {
        return;
    }
    // check if editor is enabled
    if( get_user_option( 'rich_editing' ) == 'true' )
    {
        add_filter( 'mce_external_plugins', function($plugin_array)
        {
            $plugin_array['mce_buttons'] = get_stylesheet_directory_uri().'/mce-button.js';
            return $plugin_array;
        });
    }
});
add_filter('mce_buttons', function($buttons)
{
    array_push( $buttons, 'mce_button' );
    array_push( $buttons, 'mce_dropdown' );
    array_push( $buttons, 'mce_latex' );
    return $buttons;
});

mce-button.js

(function() {

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

        // single button
        editor.addButton('mce_button', {
            text: 'Button #1',
            icon: false,
            onclick: function() {
                editor.insertContent('<p><a href="#" class="button">Mehr erfahren</a></p>');
            }
        });
        
        // dropdown and buttons
        editor.addButton( 'mce_dropdown', {
            text: 'Dropdown',
            icon: false,
            type: 'menubutton',
            menu: [
                {
                    text: 'Button #1',
                    menu: [
                        {
                            text: 'Button #1.1',
                            onclick: function() {
                                editor.insertContent('...');
                            }
                        },
                        {
                            text: 'Button #1.2',
                            onclick: function() {
                                editor.insertContent('...');
                            }
                        }
                    ]
                },
                {
                    text: 'Button #2',
                    menu: [
                        {
                            text: 'Button #2.1',
                            onclick: function() {
                                editor.insertContent('...');
                            }
                        },
                        {
                            text: 'Button #2.2',
                            onclick: function() {
                                editor.insertContent('...');
                            }
                        }
                    ]
                },
                {
                    text: 'Button #3',
                    onclick: function() {
                        editor.insertContent('...');
                    }
                }
            ]
        });
      
        editor.addButton('mce_latex', {
            text: 'Formeleditor',
            icon: 'preview',
            onclick: function() {
                    let popup = null,
                        url = 'https://latex.codecogs.com/editor_json3.php?type=url&editor=TinyMCE';
                    popup=window.open('','Formeleditor','width=700,height=450,status=1,scrollbars=yes,resizable=1');
                    if (!popup.opener) { popup.opener = self; }
                    popup.document.open();
                    popup.document.write('<!DOCTYPE html><head><script src="'+url+'" type="text/javascript"></script></head><body></body></html>');
                    popup.document.close();
            }
        });
    });

})();

/* for latex support */
TinyMCE_Add = function(name) {
    let sName = name.match( /(gif|svg)\.latex\?(.*)/ ),
        latex = unescape(sName[2]);
    latex = latex.replace(/@plus;/g,'+');
    latex = latex.replace(/&plus;/g,'+');
    latex = latex.replace(/&space;/g,' ');  
    tinymce.activeEditor.execCommand('mceInsertContent', false, '$$'+latex+'$$');
    tinymce.execCommand('mceFocus', false, tinymce.activeEditor.editorId);
}

hi can you please tell theme folder example path to put his code? I am new to wordpress