Example site.php for adding custom CKEditor configuration options - application\config\site.php

site.php

<?php
return [
    'sites' => [
        'default' => [
            'editor' => [
                'ckeditor4' => [
                    // add custom configuration options
                    // https://docs.ckeditor.com/#!/api/CKEDITOR.config
                    'custom_config_options' => [
                        // define what formatting tags to use
                        // - each element is separated with a semi-colon (no spaces)
                        // Example: use h2, h3, h4, and p only
                        'format_tags' => 'h2;h3;h4;p',
                        // remove buttons from the toolbar
                        // - each button is comma separated (no spaces)
                        // - button names are case-sensitive
                        // Example: remove the Underline, Subscript, and Superscript buttons
                        'removeButtons' => 'Underline,Subscript,Superscript'
                    ],
                    // group and order toolbar buttons
                    // - an example of how to group toolbar buttons can be found here:
                    // https://ckeditor.com/tmp/4.5.0-beta/ckeditor/samples/toolbarconfigurator/index.html
                    // Example: reorder the toolbar groups and add a row separator
                    'toolbar_groups' => [
                        ['name' => 'styles', 'groups' => ['styles']],
                        ['name' => 'links', 'groups' => ['links']],
                        ['name' => 'paragraph', 'groups' => ['paragraph']],
                        ['name' => 'about', 'groups' => ['about']],
                        ['name' => 'document', 'groups' => ['document']],
                        ['name' => 'doctools', 'groups' => ['doctools']],
                        ['name' => 'clipboard', 'groups' => ['clipboard']],
                        ['name' => 'undo', 'groups' => ['undo']],
                        ['name' => 'others', 'groups' => ['others']],
                        ['name' => 'tools', 'groups' => ['tools']],
                        // row separator
                        // - rows separators start the beginning of new rows
                        // - without them, the following buttons and button groups will not start from the left side of the toolbar
                        '/',
                        ['name' => 'find', 'groups' => ['find']],
                        ['name' => 'selection', 'groups' => ['selection']],
                        ['name' => 'spellchecker', 'groups' => ['spellchecker']],
                        ['name' => 'editing', 'groups' => ['editing']],
                        ['name' => 'basicstyles', 'groups' => ['basicstyles']],
                        ['name' => 'cleanup', 'groups' => ['cleanup']],
                        ['name' => 'list', 'groups' => ['list']],
                        ['name' => 'mode', 'groups' => ['mode']],
                        ['name' => 'indent', 'groups' => ['indent']],
                        ['name' => 'blocks', 'groups' => ['blocks']],
                        ['name' => 'align', 'groups' => ['align']],
                        ['name' => 'bidi', 'groups' => ['bidi']],
                        ['name' => 'insert', 'groups' => ['insert']],
                        ['name' => 'forms', 'groups' => ['forms']],
                        ['name' => 'colors', 'groups' => ['colors']],
                    ],
                    // add custom JavaScript configuration options
                    'editor_function_options' => <<<'EOD'
                        console.log('goat milk fudge');

                        CKEDITOR.on('dialogDefinition', function(event) {
                            // get the dialog name and its definition from the event data
                            var dialogName = event.data.name;
                            var dialogDefinition = event.data.definition;
                            // check if the definition is from the dialog we are looking for
                            // Example: link plugin dialog
                            if (dialogName === 'link') {
                                // remove a tab and all of its contents
                                // Example: remove the Advanced tab from the Link plugin
                                // dialogDefinition.removeContents('advanced');

                                // get the dialog definition contents for a specific tab
                                // - remove the fields by name
                                // Example: get the Advanced tab contents and remove individual fields
                                var advancedTab = dialogDefinition.getContents('advanced');
                                advancedTab.remove('advAccessKey');
                                advancedTab.remove('advName');
                                advancedTab.remove('advLangCode');
                                advancedTab.remove('advTabIndex');
                                advancedTab.remove('advRel');
                                advancedTab.remove('advCharset');
                                advancedTab.remove('advStyles');
                                advancedTab.remove('advTitle');
                                advancedTab.remove('advContentType');
                                advancedTab.remove('advLangDir');
                            }
                            // Example: image plugin dialog
                            if (dialogName === 'image') {
                                // remove a tab and all of its contents
                                // - the tab id is what you will use to remove the tab
                                // - the tab id is case-sensitive
                                // Example: remove the Link tab from the Image plugin
                                dialogDefinition.removeContents('Link');
                            }
                        });
EOD
// if additional arrays are added after editor_function_options, the comma must be on the next line, not on the same line as EOD
                ]
            ]
        ]
    ]
];