Taking CKEditor a Apart

In this post, we dive into the code of CKEditor to learn internals. We needed to do so to understand how the empty tags are being removed by default. This was not acceptable behavior because frameworks like Twitter Bootstrap or Foundation use empty tags part of the layout.

The dev version none minimized CKEditor are located at https://github.com/ckeditor/ckeditor-dev

Boot from Console

When troubleshooting or learning, it always easer to move everything else out of the way but the thing of your interest. In our case, we decided to run CKEditor without Drupal in the browser console for quick, easy changes. In the following are steps to boot CKEditor from console:

1. Disable Drupal

To take Drupal out of way, we disable the CKEditor module

2. Import CKEditor

There were several ways to load CKEditor all of which are listed here

A)From HTML Layout
By inserting the following in top of your page within ‘head’ tag

<script src="http://dev-ckeditor/sites/all/libraries/ckeditor/ckeditor.js?n83a0r"></script>

B) From Drupal API
By executing the following code in hook_preprocess_page() or any other appropriate place for that matter

drupal_add_js('http://dev-ckeditor/sites/all/libraries/ckeditor/ckeditor.js', array('scope' =>; 'header', 'type' =>; 'external'));

C)From JS Console
By calling the following, ckeditor library will be loaded


NOTE: In console, I run into errors when ckeditor.js was trying to load its dependences such ad load.js due to unable configure base path. I believe it should work if using the production ckeditor.js instead the development version that is not compiled into one

This will import the library as well as initialize CKeditor after which making the global variable CKEDITOR available and ready, so we can call CKEditor API

Let’s check the status


It gives status – ‘loaded’ on success and its ready to start ckeditor
There are 4 different status – loaded, basic_load, ???

4. Load Into Textarea

To start up CKEditor in the textarea is as simple as initializing it that can be done from console as following:

//or particular element with certain id

Here, we start up all of the textareas by calling replaceAll(). In the second, we enable CKEditor on certain element not necessaryly ‘textarea’ with id of ‘id_name’. This should bring up the text editor

Other Stuff

1. Editor Instances

This will display all the ckeditor instances

2. See Editor Configuration

From console:

var editor = CKEDITOR.instances.editor1;
alert( editor.config.skin ); // e.g. 'moono'
3. Filters

To see what input is about to be filtered:


Setting custom filters:

var filter = new CKEDITOR.filter( 'p strong em br' );
editor.setActiveFilter( filter );
// Create standalone filter passing 'p' and 'b' elements.
		 *		var filter = new CKEDITOR.filter( 'p b' ),
		 *			// Parse HTML string to pseudo DOM structure.
		 *			fragment = CKEDITOR.htmlParser.fragment.fromHtml( '<p><b>foo</b> <i>bar</i></p>' ),
		 *			writer = new CKEDITOR.htmlParser.basicWriter();
		 *		filter.applyTo( fragment );
		 *		fragment.writeHtml( writer );
		 *		writer.getHtml(); // -> '<p><b>foo</b> bar</p>'

For hooking into all enable active filters:

editor.on( 'activeFilterChange', function() {
     if ( editor.activeFilter.check( 'cite' ) )
        // Do something when <cite> was enabled - e.g. enable a button.
        // Otherwise do something else.
   } );

To disable filters:

//before the editor is initiated
 CKEDITOR.config.allowedContent = true;
textarea_settings = Drupal.ckeditorLoadPlugins(textarea_settings);
CKEDITOR.replace(textarea_id, textarea_settings);

Here, the textarea_id is the ‘id’ of the element(textarea or div). I am not sure the textarea_settigns???

5. Drupal and CKEditor

In the modules/ckeditor/ckeditor.utils.js, is where the CKEditor instances are created and attached to textarea.
From ckeditor.utils.js, the function CKEditor.replace is called that is defined in the themedui.js that calls CKEDITOR.editor from editor.js

6. Fragmenting in CKEditor
var fragment = CKEDITOR.htmlParser.fragment.fromHtml( '<p>foo<b>bar</b>bom</p>' );
 fragment.forEach( function( node ) {
 console.log( node );
} );
		 *		// Will log:
		 *		// 1. document fragment,
		 *		// 2. <p> element,
		 *		// 3. "foo" text node,
		 *		// 4. <b> element,
		 *		// 5. "bar" text node,
		 *		// 6. "bom" text node.
		 * @since 4.1
		 * @param {Function} callback Function to be executed on every node.
		 * **Since 4.3** if `callback` returned `false` descendants of current node will be ignored.
		 * @param {CKEDITOR.htmlParser.node} callback.node Node passed as argument.
		 * @param {Number} [type] If specified `callback` will be executed only on nodes of this type.
		 * @param {Boolean} [skipRoot] Don't execute `callback` on this fragment.
7. Stop Removing Empty Tags

There is defined list of tags that is going to be removed if empty(see dtd.js and $removeEmpty). To ensure the certain empty tag are not being removed, add attribute ‘data-cke-survive’:

<span data-cke-survive="true" ></span>

or pass the following to the CKEditor configuration file:

CKEDITOR.dtd.$removeEmpty['span'] = 0;
CKEDITOR.dtd.$removeEmpty['TAG-NAME'] = 0;

This make the empty tags to not being removed
NOTE: If you working with the production CKEditor.js, you will have to alter section starting “CKEDITOR.dtd” as following:

 CKEDITOR.dtd=function(){var a=CKEDITOR.tools.extend,e=function(a,d){for(var [...]
span:0//set the 

You will have to grep the CKEditor.js file for section starting “CKEDITOR.dtd” and then change value from 1 to 0 for each tags you like to not be removed if empty(see above example for ‘span’ tag)

8. Update Styles

Here is an example for console to update styles:

var editor = CKEDITOR.instances['edit-body-und-0-value'];

Here, we start by retrieving the CKEditor Instance with id “edit-body-und-0-value”. Afterwards, we set the font-size.

if you like append the whole style sheet than:

9. Stop Auto Wrap

The default behavior is for CKEditor to wrap text into paragraph tags. To stop that:

//from console
CKEDITOR.config['autoParagraph'] = false

In the ckeditor.config.js file:

config.autoParagraph = false

This will stop automatically wrapping every element into paragraph tag. You can also set to add ‘br’ or ‘div’ instead of pargraph tags as following:

CKEDITOR.config['entermode'] = CKEDITOR.ENTER_BR;//or config.entermode=2 in config.js
CKEDITOR.config['entermode'] = CKEDITOR.ENTER_DIV;//or config.entermode=23 in config.js

This will add BR or DIV tag to every element

To stop wrap a certain element such as anchor tag into paragraph tag:

                delete CKEDITOR.dtd.$inline['a'];

This will change the declaration of the anchor tag to not be an inline tag, thus, no any wrapping takes place

Stop remove Empty Anchor tags

To stop removing empty tags, add the attribute – “data-cke-survive” to the anchor tag as following:

<a href="#" data-original-title="github" class="github" data-cke-survive="true">

Or ensure attribute “href” is not present as following:

<a data-original-title="linkedin" class="linkedin">
Stop Wrap UL around LI

By default, CKeditor is wrapping UL element around LI if one is not present. To stop alter CKEDITOR.dtd.$listItem in DTD.js

//OLD:$listItem: { dd: 1, dt: 1, li: 1 },
        $listItem: { dd: 1, dt: 1},

By editing CKEditor directly will cause problems sooner or later. Instead, hook into CKeditor and update from outside

                CKEDITOR.on('instanceCreated', function (ev) {
                  //make sure LI is not wrapped within UL
                    delete CKEDITOR.dtd.$listItem['li'];
                    delete CKEDITOR.dtd.$intermediate['li'];    

Here, we hook into the event triggered when CKEditor instance is created to remove “li’ tag from inline tags list.
By removing the LI form the list, you ensure that CKEditor is not wrapping LI elements with additional “UL”. For production, you will have to grep ckeditor.js file to make the change since everything is compiled into one JS file

Hook Into Events

There are lot of events available either on CKEDITOR App variable – CKEDITOR or on each editor instance itself

To listen for event on CKEDITOR APP variable

CKEDITOR.on( 'instanceReady', function( ev ) {
    editor = ev.editor;
    if(editor.name == 'edit-body-value'){
         console.log( 'appending style - sites/all/themes/metronic/assets/drupal/custom_metronic.css' );

Here, we sign up for event “InstanceReady” to append custom stylesheets.

To listen for event on editor instance itself

CKEDITOR.on( 'instanceCreated', function( ev ) {
    if(ev.editor.name == 'edit-body-value'){
       ev.editor.on( 'contentDom', function(){
         var ck_dom = ev.editor.document.$;
         var s0= ck_dom.createElement( 'script' );
         s0.type = 'text/javascript';
         s0.onload = function() {
             console.log( 'script /path/jquery-1.11.0.min.js loaded' );
         s0.src = '/path/jquery-1.11.0.min.js';
         s0.$ = s0;
      } );

Here, we first use event on the CKEDITOR App itself to get handle of the editor obj. Once we got the editor object, we sign up for an event “contentDom” that is triggered once the DOM of editor content is constructed. During this event we are importing JQuery lib

See What’s Going On

To see what is filtered, processed and actually sitting in the editor content(DOM) at any give time from console:

var editor = CKEDITOR.instances['edit-body-value'];
editor.document.$.body //to see what is within BODY tags
editor.document.$.head //to see what is within HEAD tags

Here, we first retrieve the particular textarea of our interest and then navigate to the BODY or HEAD. It will display the DOM in real time

How To Find Which Config.js CKEditor Is Using

To see which config.js the CKEditor is actually using, once the instance is up, go to console and type:


This will print out the path and the name of config file CKEditor is using. Note, there may be different config files used at the same time. The CKEDITOR app using one and then each different editor instance(i.e.CKEDITOR.instances.editor1) using another one(perhaps one loaded from the theme folder,etc)

Some Tags are Removed

you can disable the filter with allowedContent configuration as described above. You can also disable processing on a particular tag as following:

  • data-cke-filter=”off”
  • data-cke-processor=”off”
  • autocomplete=”off”

This will apply for the tag and all of its children

Manipulate Editor Content

To remove some element from the the editor:

var element = ev.editor.document.getById( 'ckeditor-wrapper-end' );

This will remove element with id ckeditor-wrapper-end while keeping parent and children elements intact.
The better way API for manipulated data of editor is available on “editable” object:

var editable = CKEDITOR.instances['.textId'].editor.editable();
if(editable.find('ckeditor-wrapper-end').count()) editable.find('.ckeditor-wrapper-end').remove();

As you can see, the “editable” API has similar API as jQuery. Please, reference editable.js for complete list of function available.

Update Editor

To update editor content:

var editor = CKEDITOR.instances['TEXTAREA-ID'];
var newHtml = '<p>Hello World!</p>";
       callback: function() {

Here, we first retrieve editor and then update its content via setData() API. At last, the textarea itself is updated in the DOM

Summary of Events

Event Scope comments
loaded editor triggered once editor is loaded before initiating the editor content
instanceLoaded CKEDITOR triggered once CKEDITOR is loaded
customConfigLoaded editor
configLoaded editor
destroy editor
save editor
key editor
dblclick editor
doubleclick editor
click editor
beforeGetData editor Handle the load/read of editor data/snapshot.
getSnapshot editor sets event data from the editor data
saveSnapshot editor ???
lockSnapshot editor ???
unlockSnapshot editor ???
afterSetData editor sets the data from editor data
loadSnapshot editor takes event data and sets it to the editor data
beforeFocus editor Delegate editor focus/blur to editable.
insertHtml editor takes the data from event and inserts in CKEDITOR.DOM via insertHTML()
insertElement editor takes the data from event and inserts in CKEDITOR.DOM via insertElement()
insertText editor takes the data from event and inserts in CKEDITOR.DOM via insertText()
beforeSetMode editor Before any mode is set on the Editor(i.e. editor.mode)(see plugin.js)
beforeModeUnload editor after mode is set on the editor(i.e. editor.mode)(see plugin.js)
beforeGetModeData editor before getting data after setting the mode(see plugin.js)
afterModeUnload editor passing data to be able update at last step in mode setup(see plugin.js)
toHtml editor at the time data is process including filters applied(see htmlprocessor.js)
dataFiltered editor after some filter applied(see htmldataprocessor.js)
dataReady editor when data is ready before processing and filtering(see htmldataprocessor.js)

To fire any of the events:

editor.fire( 'saveSnapshot' );

Here, we trigger one of the events – saveSnapshot attached to the editor.
To listen an event:

			editor.on( 'saveSnapshot', function( evt ) {
                                //do something with evt.data or evt.data.contentOnly
			} );

Here we listen of event – save Snapshot and then grab the new data via evt.data or evt.data.contentOnly

Encode and Decode

To decode or encode a string:

var result = CKEDITOR.tools.htmlDecode(editor.getData());
var encodedText = CKEDITOR.tools.htmlEncode(result);

Here, the editor data is decoded and encoded. See CKEDITOR.tools for much more utilities


1.Resource interpreted as Script but transferred with MIME type text/html: “http://dev-ckeditor/node/add/core/loader.js”

This happened when I was trying to load CKEditor library from console and the CKEditor was trying to load its dependencies. The dependency URL(path) came up wrong resulting in this error. I tried to set CKEditor Base path but it didn’t work because the base path needed to be set before the CKEdiotr library is loaded. I tried that and it didn’t work

The changes doesn’t take an effect

Make sure you clear browser cache as well as Drupal cache for the most current config.js loaded

One thought on “Taking CKEditor a Apart

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