HOW_TO_CREATE_A_PLUGIN.md

---

Basics

A Plugin is simply a plain JavaScript object containing a couple deeper nested objects or functions e.g.

const customPlugin = {
  blockStyleFn: (contentBlock) => {
    if (contentBlock.getType() === 'blockquote') {
      return 'superFancyBlockquote';
    }
  },
  customStyleMap: {
    'STRIKETHROUGH': {
      textDecoration: 'line-through',
    },
  },
};

As most plugins take some kind of configuration we recommend you to always export a function that creates this object. This is aligned with all the core plugins and leads to a consistent developer experience.

export default createCustomPlugin = (config) => {
  const blockStyleFn = (contentBlock) => {
    if (contentBlock.getType() === 'blockquote') {
      return 'superFancyBlockquote';
    }
  };
  
  const customStyleMap = {
    'STRIKETHROUGH': {
      textDecoration: 'line-through',
    },
  };

  return {
    blockStyleFn: blockStyleFn,
    customStyleMap: customStyleMap,
  };
};

Supported Objects & Hooks

A plugin accepts all standard props the Draft.js Editor Component uses. See details on Draft.js docs. Commonly used props:

• blockRendererFn
• keyBindingFn
• blockStyleFn
• blockRenderMap
• customStyleMap
• handleReturn
• handleKeyCommand
• handleBeforeInput
• handlePastedText
• handlePastedFiles
• handleDroppedFiles
• handleDrop
• onEscape
• onTab
• onUpArrow
• onRightArrow
• onDownArrow
• onLeftArrow
• onFocus
• onBlur

There is one difference compared to the original properties. All functions receive an additional argument. This argument is an object containing:

// PluginFunctions
{
  getPlugins, // a function returning a list of all the plugins
  getProps, // a function returning a list of all the props pass into the Editor
  setEditorState, // a function to update the EditorState
  getEditorState, // a function to get the current EditorState
  getReadOnly, // a function returning of the Editor is set to readOnly
  setReadOnly, // a function which allows to set the Editor to readOnly
  getEditorRef, // a function to get the editor reference
}

In addition the a plugin accepts

• initialize: (PluginFunctions) => void
• onChange: (EditorState, PluginFunctions) => EditorState
• willUnmount: (PluginFunctions) => void
• decorators: Array<Decorator> => void
• getAccessibilityProps: () => { ariaHasPopup: string, ariaExpanded: string }

---

initialize

Allows to initialize a plugin once the editor becomes mounted.

onChange

Allows a plugin to modify the state at the latest moment before the onChange callback of the Draft.js Editor is fired.

willUnmount

Usually used to clean up.

decorators

Draft.js allows to initialize an EditorState with a decorator. Many plugins also rely on decorators and therefore we decided to incorporate them in the plugin architecture. Every plugin can have multiple decorators and all of them are combined by the plugin editor.

A decorator can contain a strategy and a component e.g.

{
  decorators: [
    {
      strategy: hashtagStrategy,
      component: HashtagSpan,
    },
  ],
}

You can read more about it in the original Draft.js documentation about decorators.

If you want to implement the DraftDecoratorType Interface yourself, you can include those in your decorators array alongside the composite decorators. See draft-js-simpledecorator for an example of an implementation of DraftDecoratorType. Here's an example mixed decorators array:

{
  decorators: [
    {
      strategy: hashtagStrategy,
      component: HashtagSpan,
    },
    new MyCustomDraftDecoratorType('...'),
  ],
}

getAccessibilityProps

In some rare cases like @mentions or Emoji autocompletion a plugin should be able to set certain ARIA attributes. This currently only allows to set aria-has-popup & aria-expanded. Let us know in case you have further suggestions.

Further Information

Keep in mind that the order of plugins can matter. The first decorator the that matches prevents the following ones to become active for a certain text block. Same goes for handleReturn if returned true. Therefor try to keep your plugins minimal in the sense that they only match & manipulate the necessary block or text.