Plugins can be attached to an editor to alter its behavior in different ways. Plugins are just simple Javascript objects, containing a set of properties that control different behaviors—event handling, change handling, rendering, etc.
Each editor has a "middleware stack" of plugins, which has a specific order.
When the editor needs to resolve a plugin-related handler, it will loop through its plugin stack, searching for the first plugin that successfully returns a value. After receiving that value, the editor will not continue to search the remaining plugins; it returns early.
A plugin should always export a function that takes options. This way even if it doesn't take any options now, it won't be a breaking API change to take more options in the future. So a basic plugin might look like this:
export default MySlatePlugin(options) {
return {
// Return properties that describe your logic here...
}
}{
onBeforeInput: Function,
onBlur: Function,
onCopy: Function,
onCut: Function,
onDrop: Function,
onKeyDown: Function,
onPaste: Function,
onSelect: Function
}All of the event handler properties are passed the same React event object you are used to from React's event handlers. They are also passed a data object with Slate-specific information relating to the event, the current state of the editor, and the editor instance itself.
Each event handler can choose to return a new state object, in which case the editor's state will be updated. If nothing is returned, the editor will simply continue resolving the plugin stack.
Function onBeforeInput(event: Event, data: Object, state: State, editor: Editor) => State || Void
This handler is called right before a string of text is inserted into the contenteditable element.
Make sure to event.preventDefault() if you do not want the default insertion behavior to occur! If no other plugin handles this event, it will be handled by the Core plugin.
Function onBlur(event: Event, data: Object, state: State, editor: Editor) => State || Void
This handler is called when the editor's contenteditable element is blurred.
If no other plugin handles this event, it will be handled by the Core plugin.
Function onCopy(event: Event, data: Object, state: State, editor: Editor) => State || Void
This handler is called when the editor's contenteditable element is blurred.
The data object contains a type string and associated data for that type. Right now the only type supported is "fragment":
{
type: 'fragment',
fragment: Document
}If no other plugin handles this event, it will be handled by the Core plugin.
Function onCut(event: Event, data: Object, state: State, editor: Editor) => State || Void
This handler is equivalent to the onCopy handler.
If no other plugin handles this event, it will be handled by the Core plugin.
Function onDrop(event: Event, data: Object, state: State, editor: Editor) => State || Void
This handler is called when the user drops content into the contenteditable element. The event is already prevented by default, so you must define a state change to have any affect occur.
The data object is a convenience object created to standardize the drop metadata across browsers. Every data object has a type property, can be one of text, html or files, and a target property which is a Selection indicating where the drop occured. Depending on the type, it's structure will be:
{
type: 'text',
target: Selection,
text: String
}
{
type: 'html',
target: Selection,
text: String,
html: String
}
{
type: 'files',
target: Selection,
files: FileList
}If no other plugin handles this event, it will be handled by the Core plugin.
Function onKeyDown(event: Event, data: Object, state: State, editor: Editor) => State || Void
This handler is called when any key is pressed in the contenteditable element, before any action is taken.
The data object contains the key which is a string name of the key that was pressed, as well as it's code. It also contains a series of helpful utility properties for determining hotkey logic. For example, isCtrl which is true if the control key was pressed, or
{
key: String,
code: Number,
isAlt: Boolean,
isCmd: Boolean,
isCtrl: Boolean,
isLine: Boolean,
isMeta: Boolean,
isMod: Boolean,
isModAlt: Boolean,
isShift: Boolean,
isWord: Boolean
}The isMod boolean is true if the control key was pressed on Windows or the command key was pressed on Mac without the alt/option key was also being pressed. This is a convenience for adding hotkeys like command+b.
The isModAlt boolean is true if the control key was pressed on Windows or the command key was pressed on Mac and the alt/option key was also being pressed. This is a convenience for secondary hotkeys like command+option+1.
The isLine and isWord booleans represent whether the "line modifier" or "word modifier" hotkeys are pressed when deleteing or moving the cursor. For example, on a Mac option + right moves the cursor to the right one word at a time.
Make sure to event.preventDefault() if you do not want the default insertion behavior to occur! If no other plugin handles this event, it will be handled by the Core plugin.
Function onPaste(event: Event, data: Object, state: State, editor: Editor) => State || Void
This handler is called when the user pastes content into the contenteditable element. The event is already prevented by default, so you must define a state change to have any affect occur.
The data object is a convenience object created to standardize the paste metadata across browsers. Every data object has a type property, which can be one of text, html or files. Depending on the type, it's structure will be:
{
type: 'text',
text: String
}
{
type: 'html',
text: String,
html: String
}
{
type: 'files',
files: FileList
}If no other plugin handles this event, it will be handled by the Core plugin.
Function onSelect(event: Event, data: Object, state: State, editor: Editor => State || Void
This handler is called whenever the native selection changes.
The data object contains a State Selection object representing the new selection.
If no other plugin handles this event, it will be handled by the Core plugin.
{
renderDecorations: Function,
renderMark: Function,
renderNode: Function
}To customize the renderer output of the editor, plugins can define a set of "renderer" properties.
Function renderDecorations(text: Text, state: State, editor: Editor) => Characters || Void
The renderDecorations handler allows you to add dynamic, content-aware Marks to ranges of text, without having them show up in the serialized state of the editor. This is useful for things like code highlighting, where the marks will change as the user types.
renderDecorations is called for every text node in the document, and should return a set of updated Characters for the text node in question. Every plugin's decoration logic is called, and the resulting characters are unioned, such that multiple plugins can apply decorations to the same pieces of text.
Function renderMark(mark: Mark, marks: Set, state: State, editor: Editor) => Component || Object || String || Void
The renderMark handler allows you to define the styles that each mark should be rendered with. It is passed a mark and the set of marks, and should return either a React component, an object of styles, or a class string. For example any of these are valid return values:
function Bold(props) {
return <strong>{props.children}</strong>
}
function renderMark(mark) {
if (mark.type == 'bold') return Bold
}function renderMark(mark) {
if (mark.type == 'bold') {
return {
fontWeight: 'bold'
}
}
}function renderMark(mark) {
if (mark.type == 'bold') return 'my-bold-class'
}Function renderNode(node: Block || Inline, state: State, editor: Editor) => Component || Void
The renderNode handler allows you to define the component that will be used to render a node—both blocks and inlines. It takes a Node object, and should return a React component.
The component will be called with a set of properties:
<Component
attributes={Object}
children={Any}
node={Node}
state={State}
/>attributes— a dictionary of attributes that you must add to the top-level element of the rendered component. Using the Object Spread Syntax (Stage 2) this is as easy as...props.attributes.children— a set of React element children that you must render as the leaf element in your component.node— the node being rendered.state— the current state of the editor.
Such that a simple code block renderer might look like this:
const CodeBlockRenderer = (props) => {
return (
<pre {...props.attributes}>
<code>
{props.children}
</code>
</pre>
)
} The node itself is passed in, so you can access any custom data associated with it via its data property.
{
onChange: Function
}Function onChange(state: State) => State || Void
The onChange handler isn't a native browser event handler. Instead, it is invoked whenever the editor state changes. Returning a new state will update the editor's state, continuing down the plugin stack.
Unlike the native event handlers, results from the onChange handler are cummulative! This means that every plugin in the stack that defines an onChange handler will have its handler resolved for every change the editor makes; the editor will not return early after the first plugin's handler is called.
This allows you to stack up changes across the entire plugin stack.
Function onBeforeChange(state: State) => State || Void
The onBeforeChange handler isn't a native browser event handler. Instead, it is invoked whenever the editor receives a new state and before propagating a new state to onChange. Returning a new state will update the editor's state before rendering, continuing down the plugin stack.
Like onChange, onBeforeChange is cummulative.