HTML Output Formatting

CKEditor 4 offers a powerful and flexible output formatting system. It gives developers full control over what the HTML code produced by the editor will look like. The system makes it possible to control all HTML tags and can give different results for each one of them.

# The HTML Output Writer

The HTML Output Writer plugin makes it possible to generate advanced output formatting with CKEditor 4.

The writer is used by the CKEDITOR.htmlDataProcessor class to write output data.
The current writer for a specific editor instance can be retrieved with the editor.dataProcessor.writer property.

It is possible to configure several output formatting options by setting the writer properties. The following example summarizes the most common properties and gives their default values:

var writer = editor.dataProcessor.writer;

// The character sequence to use for every indentation step.
writer.indentationChars = '\t';

// The way to close self-closing tags, like <br/>.
writer.selfClosingEnd = ' />';

// The character sequence to be used for line breaks.
writer.lineBreakChars = '\n';

// The writing rules for the <p> tag.
writer.setRules( 'p', {
    // Indicates that this tag causes indentation on line breaks inside of it.
    indent: true,

    // Inserts a line break before the <p> opening tag.
    breakBeforeOpen: true,

    // Inserts a line break after the <p> opening tag.
    breakAfterOpen: true,

    // Inserts a line break before the </p> closing tag.
    breakBeforeClose: false,

    // Inserts a line break after the </p> closing tag.
    breakAfterClose: true
} );

# Setting Writer Rules

Since the writer is a property of each editor instance and also due to its dependency on the HTML Output Writer plugin to be loaded, the best way to modify it is by listening to the event-instanceReady event, so it is safe to assume that the dataProcessor property will be loaded and ready for changes. The following code shows an example of this approach used when creating an editor instance:

CKEDITOR.replace( 'editor1', {
    on: {
        instanceReady: function( ev ) {
            // Output paragraphs as <p>Text</p>.
            this.dataProcessor.writer.setRules( 'p', {
                indent: false,
                breakBeforeOpen: true,
                breakAfterOpen: false,
                breakBeforeClose: false,
                breakAfterClose: true
            });
        }
    }
} );

Another solution is to use the CKEDITOR object which will cause all editor instances to be changed:

CKEDITOR.on( 'instanceReady', function( ev ) {
    // Ends self-closing tags the HTML4 way, like <br>.
    ev.editor.dataProcessor.writer.selfClosingEnd = '>';
});

# Adjusting Output Formatting Through Configuration

Numerous configuration options let you tweak CKEditor 4 behavior without touching the writer, including:

Entities support:
White space usage:
- dataIndentationChars
- sourceAreaTabSize
Handling block elements:
- autoParagraph (deprecated)
- fillEmptyBlocks
- ignoreEmptyParagraph
HTML encoding:
- htmlEncodeOutput