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Applying Custom Formatting
Up to now, everything we've learned has been about how to write one-off logic for your specific Slate editor. But one of the most beautiful things about Slate is actually its plugin system, and how it lets you write less one-off code.
In the previous guide, we actually wrote some pretty useful code for adding bold formatting to ranges of text when a key is pressed. But most of that code wasn't really specific to bold text; it could just as easily have applied to italic text or code text if we switched a few variables.
So let's break that logic out into it's a reusable plugin that can toggle any mark on any key press.
Starting with our app from earlier:
const BOLD_MARK = {
fontWeight: 'bold'
}
class App extends React.Component {
constructor(props) {
super(props)
this.state = {
state: initialState
}
}
render() {
return (
<Editor
state={this.state.state}
renderMark={mark => this.renderMark(mark)}
onChange={state => this.onChange(state)}
onKeyDown={(e, state) => this.onKeyDown(e, state)}
/>
)
}
renderMark(mark) {
if (mark.type == 'bold') return BOLD_MARK
}
onChange(state) {
this.setState({ state })
}
onKeyDown(event, state) {
if (!event.metaKey || event.which != 66) return
const isBold = state.marks.some(mark => mark.type == 'bold')
return state
.transform()
[isBold ? 'removeMark' : 'addMark']('bold')
.apply()
}
}Let's write a new function, that takes a set of options: the mark type to toggle and the key code to press.
function MarkHotkey(options) {
// Grab our options from the ones passed in.
const { type, code } = options
}Okay, that was easy. But it doesn't do anything.
To fix that, we need our plugin function to return a "plugin object" that Slate recognizes. Slate's plugin objects are just plain objects that have properties that map to the same handler on the Editor.
In this case our plugin object will have one property: a onKeyDown handler, with its logic copied right from our current app's code:
function MarkHotkey(options) {
const { type, code } = options
// Return our "plugin" object, containing the `onKeyDown` handler.
return {
onKeyDown(event, state) {
// Check that the key pressed matches our `code` option.
if (!event.metaKey || event.which != code) return
// Determine whether our `type` option mark is currently active.
const isActive = state.marks.some(mark => mark.type == type)
// Toggle the mark `type` based on whether it is active.
return state
.transform()
[isActive ? 'removeMark' : 'addMark'](type)
.apply()
}
}
}Boom! Now we're getting somewhere. That code is reusable for any type of mark.
Now that we have our plugin, let's remove the hard-coded logic from our app, and replace it with our brand new MarkHotkey plugin instead, passing in the same options that will keep our bold functionality intact:
const BOLD_MARK = {
fontWeight: 'bold'
}
// Initialize our bold-mark-adding plugin.
const boldPlugin = MarkHotkey({
type: 'bold',
code: 66
})
// Create an array of plugins.
const plugins = [
boldPlugin
]
class App extends React.Component {
constructor(props) {
super(props)
this.state = {
state: initialState
}
}
// Add the `plugins` property to the editor, and remove `onKeyDown`.
render() {
return (
<Editor
state={this.state.state}
plugins={plugins}
renderMark={mark => this.renderMark(mark)}
onChange={state => this.onChange(state)}
/>
)
}
renderMark(mark) {
if (mark.type == 'bold') return BOLD_MARK
}
onChange(state) {
this.setState({ state })
}
}Awesome. If you test out the editor now, you'll notice that everything still works just as it did before. But the beauty of the logic being encapsulated in a plugin is that we can add more mark types extremely easily now!
Let's add italic, code, strikethrough and underline marks:
// Add our new mark renderers...
const MARKS = {
bold: {
fontWeight: 'bold'
},
code: {
fontFamily: 'monospace'
},
italic: {
fontStyle: 'italic'
},
strikethrough: {
textDecoration: 'strikethrough'
},
underline: {
textDecoration: 'underline'
}
}
// Initialize our plugins...
const plugins = [
MarkHotkey({ code: 66, type: 'bold' }),
MarkHotkey({ code: 192, type: 'code' }),
MarkHotkey({ code: 73, type: 'italic' }),
MarkHotkey({ code: 68, type: 'strikethrough' }),
MarkHotkey({ code: 85, type: 'underline' })
]
class App extends React.Component {
constructor(props) {
super(props)
this.state = {
state: initialState
}
}
render() {
return (
<Editor
state={this.state.state}
plugins={plugins}
renderMark={mark => this.renderMark(mark)}
onChange={state => this.onChange(state)}
/>
)
}
// Update our render function to handle all the new marks...
renderMark(mark) {
return MARKS[mark.type]
}
onChange(state) {
this.setState({ state })
}
}And there you have it! We just added a ton of functionality to the editor with very little work. And we can keep all of our mark hotkey logic tested and isolated in a single place, making maintaining the code easier.
Of course... now that it's reusable, we could actually make our MarkHotkey plugin a little easier to use. What if instead of a code argument it took the text of the key itself? That would make the calling code a lot clearer, since key codes are really obtuse.
In fact, unless you have weirdly good keycode knowledge, you probably have no idea what our current hotkeys actually are.
Let's fix that.
Using the keycode module in npm makes this dead simple.
First install it:
npm install keycode
And then we can add it our plugin:
// Import the keycode module.
import keycode from `keycode`
function MarkHotkey(options) {
// Change the options to take a `key`.
const { type, key } = options
return {
onKeyDown(event, state) {
// Change the comparison to use the key name.
if (!event.metaKey || keycode(event.which) != key) return
const isActive = state.marks.some(mark => mark.type == type)
return state
.transform()
[isActive ? 'removeMark' : 'addMark'](type)
.apply()
}
}
}And now we can make our app code much clearer for the next person who reads it:
const MARKS = {
bold: {
fontWeight: 'bold'
},
code: {
fontFamily: 'monospace'
},
italic: {
fontStyle: 'italic'
},
strikethrough: {
textDecoration: 'strikethrough'
},
underline: {
textDecoration: 'underline'
}
}
// Use the much clearer key names instead of key codes!
const plugins = [
MarkHotkey({ key: 'b', type: 'bold' }),
MarkHotkey({ key: '`', type: 'code' }),
MarkHotkey({ key: 'i', type: 'italic' }),
MarkHotkey({ key: 'd', type: 'strikethrough' }),
MarkHotkey({ key: 'u', type: 'underline' })
]
class App extends React.Component {
constructor(props) {
super(props)
this.state = {
state: initialState
}
}
render() {
return (
<Editor
state={this.state.state}
plugins={plugins}
renderMark={mark => this.renderMark(mark)}
onChange={state => this.onChange(state)}
/>
)
}
renderMark(mark) {
return MARKS[mark.type]
}
onChange(state) {
this.setState({ state })
}
}That's why plugins are awesome. They let you get really expressive while also making your codebase easier to manage. And since Slate is built with plugins as a primary consideration, using them is dead simple!
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Saving to a Database