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Add to an existing extension

Every extension has an extend() method, which takes an object with everything you want to change or add to it.

Let’s say, you’d like to change the keyboard shortcut for the bullet list. You should start with looking at the source code of the extension, in that case the BulletList node. For the bespoken example to overwrite the keyboard shortcut, your code could look like this:

// 1. Import the extension
import BulletList from '@tiptap/extension-bullet-list'

// 2. Overwrite the keyboard shortcuts
const CustomBulletList = BulletList.extend({
  addKeyboardShortcuts() {
    return {
      'Mod-l': () => this.editor.commands.toggleBulletList(),
    }
  },
})

// 3. Add the custom extension to your editor
new Editor({
  extensions: [
    CustomBulletList(),
    // …
  ],
})

The same applies to every aspect of an existing extension, except to the name. Let’s look at all the things that you can change through the extend method. We focus on one aspect in every example, but you can combine all those examples and change multiple aspects in one extend() call too.

Name

The extension name is used in a whole lot of places and changing it isn’t too easy. If you want to change the name of an existing extension, you can copy the whole extension and change the name in all occurrences.

The extension name is also part of the JSON. If you store your content as JSON, you need to change the name there too.

Settings

All settings can be configured through the extension anyway, but if you want to change the default settings, for example to provide a library on top of Tiptap for other developers, you can do it like this:

import Heading from '@tiptap/extension-heading'

const CustomHeading = Heading.extend({
  addOptions() {
    return {
      ...this.parent?.(),
      levels: [1, 2, 3],
    }
  },
})

Storage

At some point you probably want to save some data within your extension instance. This data is mutable. You can access it within the extension under this.storage.

import { Extension } from '@tiptap/core'

const CustomExtension = Extension.create({
  name: 'customExtension',

  addStorage() {
    return {
      awesomeness: 100,
    }
  },

  onUpdate() {
    this.storage.awesomeness += 1
  },
})

Outside the extension you have access via editor.storage. Make sure that each extension has a unique name.

const editor = new Editor({
  extensions: [CustomExtension],
})

const awesomeness = editor.storage.customExtension.awesomeness

Schema

Tiptap works with a strict schema, which configures how the content can be structured, nested, how it behaves and many more things. You can change all aspects of the schema for existing extensions. Let’s walk through a few common use cases.

The default Blockquote extension can wrap other nodes, like headings. If you want to allow nothing but paragraphs in your blockquotes, set the content attribute accordingly:

// Blockquotes must only include paragraphs
import Blockquote from '@tiptap/extension-blockquote'

const CustomBlockquote = Blockquote.extend({
  content: 'paragraph*',
})

The schema even allows to make your nodes draggable, that’s what the draggable option is for. It defaults to false, but you can override that.

// Draggable paragraphs
import Paragraph from '@tiptap/extension-paragraph'

const CustomParagraph = Paragraph.extend({
  draggable: true,
})

That’s just two tiny examples, but the underlying ProseMirror schema is really powerful.

Attributes

You can use attributes to store additional information in the content. Let’s say you want to extend the default Paragraph node to have different colors:

const CustomParagraph = Paragraph.extend({
  addAttributes() {
    // Return an object with attribute configuration
    return {
      color: {
        default: 'pink',
      },
    },
  },
})

// Result:
// <p color="pink">Example Text</p>

That is already enough to tell Tiptap about the new attribute, and set 'pink' as the default value. All attributes will be rendered as a HTML attribute by default, and parsed from the content when initiated.

Let’s stick with the color example and assume you want to add an inline style to actually color the text. With the renderHTML function you can return HTML attributes which will be rendered in the output.

This examples adds a style HTML attribute based on the value of color:

const CustomParagraph = Paragraph.extend({
  addAttributes() {
    return {
      color: {
        default: null,
        // Take the attribute values
        renderHTML: (attributes) => {
          // … and return an object with HTML attributes.
          return {
            style: `color: ${attributes.color}`,
          }
        },
      },
    }
  },
})

// Result:
// <p style="color: pink">Example Text</p>

You can also control how the attribute is parsed from the HTML. Maybe you want to store the color in an attribute called data-color (and not just color), here’s how you would do that:

const CustomParagraph = Paragraph.extend({
  addAttributes() {
    return {
      color: {
        default: null,
        // Customize the HTML parsing (for example, to load the initial content)
        parseHTML: (element) => element.getAttribute('data-color'),
        // … and customize the HTML rendering.
        renderHTML: (attributes) => {
          return {
            'data-color': attributes.color,
            style: `color: ${attributes.color}`,
          }
        },
      },
    }
  },
})

// Result:
// <p data-color="pink" style="color: pink">Example Text</p>

You can completely disable the rendering of attributes with rendered: false.

Extend existing attributes

If you want to add an attribute to an extension and keep existing attributes, you can access them through this.parent().

In some cases, it is undefined, so make sure to check for that case, or use optional chaining this.parent?.()

const CustomTableCell = TableCell.extend({
  addAttributes() {
    return {
      ...this.parent?.(),
      myCustomAttribute: {
        // …
      },
    }
  },
})

Global attributes

Attributes can be applied to multiple extensions at once. That’s useful for text alignment, line height, color, font family, and other styling related attributes.

Take a closer look at the full source code of the TextAlign extension to see a more complex example. But here is how it works in a nutshell:

import { Extension } from '@tiptap/core'

const TextAlign = Extension.create({
  addGlobalAttributes() {
    return [
      {
        // Extend the following extensions
        types: ['heading', 'paragraph'],
        // … with those attributes
        attributes: {
          textAlign: {
            default: 'left',
            renderHTML: (attributes) => ({
              style: `text-align: ${attributes.textAlign}`,
            }),
            parseHTML: (element) => element.style.textAlign || 'left',
          },
        },
      },
    ]
  },
})

Render HTML

With the renderHTML function you can control how an extension is rendered to HTML. We pass an attributes object to it, with all local attributes, global attributes, and configured CSS classes. Here is an example from the Bold extension:

renderHTML({ HTMLAttributes }) {
  return ['strong', HTMLAttributes, 0]
},

The first value in the array should be the name of HTML tag. If the second element is an object, it’s interpreted as a set of attributes. Any elements after that are rendered as children.

The number zero (representing a hole) is used to indicate where the content should be inserted. Let’s look at the rendering of the CodeBlock extension with two nested tags:

renderHTML({ HTMLAttributes }) {
  return ['pre', ['code', HTMLAttributes, 0]]
},

If you want to add some specific attributes there, import the mergeAttributes helper from @tiptap/core:

import { mergeAttributes } from '@tiptap/core'

// ...

renderHTML({ HTMLAttributes }) {
  return ['a', mergeAttributes(HTMLAttributes, { rel: this.options.rel }), 0]
},

Parse HTML

The parseHTML() function tries to load the editor document from HTML. The function gets the HTML DOM element passed as a parameter, and is expected to return an object with attributes and their values. Here is a simplified example from the Bold mark:

parseHTML() {
  return [
    {
      tag: 'strong',
    },
  ]
},

This defines a rule to convert all <strong> tags to Bold marks. But you can get more advanced with this, here is the full example from the extension:

parseHTML() {
  return [
    // <strong>
    {
      tag: 'strong',
    },
    // <b>
    {
      tag: 'b',
      getAttrs: node => node.style.fontWeight !== 'normal' && null,
    },
    // <span style="font-weight: bold"> and <span style="font-weight: 700">
    {
      style: 'font-weight',
      getAttrs: value => /^(bold(er)?|[5-9]\d{2,})$/.test(value as string) && null,
    },
  ]
},

This checks for <strong> and <b> tags, and any HTML tag with an inline style setting the font-weight to bold.

As you can see, you can optionally pass a getAttrs callback, to add more complex checks, for example for specific HTML attributes. The callback gets passed the HTML DOM node, except when checking for the style attribute, then it’s the value.

You are wondering what’s that && null doing? ProseMirror expects null or undefined if the check is successful.

Pass priority to a rule to resolve conflicts with other extensions, for example if you build a custom extension which looks for paragraphs with a class attribute, but you already use the default paragraph extension.

Using getAttrs

The getAttrs function you’ve probably noticed in the example has two purposes:

  1. Check the HTML attributes to decide whether a rule matches (and a mark or node is created from that HTML). When the function returns false, it’s not matching.
  2. Get the DOM Element and use the HTML attributes to set your mark or node attributes accordingly:
parseHTML() {
  return [
    {
      tag: 'span',
      getAttrs: element => {
        // Check if the element has an attribute
        element.hasAttribute('style')
        // Get an inline style
        element.style.color
        // Get a specific attribute
        element.getAttribute('data-color')
      },
    },
  ]
},

You can return an object with the attribute as the key and the parsed value to set your mark or node attribute. We would recommend to use the parseHTML inside addAttributes(), though. That will keep your code cleaner.

addAttributes() {
  return {
    color: {
      // Set the color attribute according to the value of the `data-color` attribute
      parseHTML: element => element.getAttribute('data-color'),
    }
  }
},

Read more about getAttrs and all other ParseRule properties in the ProseMirror reference.