yoanbernabeu Monaco Editor in Slidev
This skill covers integrating Monaco Editor (the editor powering VS Code) into your Slidev presentations for live coding, interactive demos, and executable code blocks.
When to Use This Skill
- Live coding demonstrations
- Interactive code editing during presentations
- Running code examples in real-time
- Teaching programming concepts
- Showing auto-completion and type hints
Enabling Monaco Editor
Basic Monaco Block
Add {monaco} to any code block:
```typescript {monaco}
const greeting = 'Hello, World!'
console.log(greeting)
```
This creates an editable code block with:
- Syntax highlighting
- Auto-completion
- Type checking (for TypeScript)
- Bracket matching
Monaco with Line Highlighting
```typescript {monaco}{2,3}
const a = 1
const b = 2 // highlighted
const c = 3 // highlighted
```
Monaco Runner
Execute code directly in the presentation:
JavaScript Runner
```javascript {monaco-run}
const numbers = [1, 2, 3, 4, 5]
const doubled = numbers.map(n => n * 2)
console.log(doubled)
```
Click "Run" to execute and see output.
TypeScript Runner
```typescript {monaco-run}
interface User {
name: string
age: number
}
const user: User = {
name: 'John',
age: 30
}
console.log(`${user.name} is ${user.age} years old`)
```
Auto-Run on Load
```javascript {monaco-run} {autorun:true}
console.log('This runs automatically!')
```
Show Output Only
```javascript {monaco-run} {showOutputAt:'+1'}
// Output shows after one click
console.log('Hello!')
```
Configuration Options
Editor Height
```typescript {monaco}{height:'300px'}
// Taller editor
function longFunction() {
// ...
}
```
Read-Only Mode
```typescript {monaco}{readonly:true}
// Cannot be edited
const CONSTANT = 'value'
```
Diff Editor
```typescript {monaco-diff}
const original = 'Hello'
~~~
const modified = 'Hello, World!'
```
Monaco Setup Configuration
setup/monaco.ts
import { defineMonacoSetup } from '@slidev/types'
export default defineMonacoSetup((monaco) => {
// Editor options
return {
editorOptions: {
fontSize: 14,
fontFamily: 'JetBrains Mono, monospace',
minimap: { enabled: false },
lineNumbers: 'on',
wordWrap: 'on',
tabSize: 2,
scrollBeyondLastLine: false,
automaticLayout: true,
},
// Light/dark theme
theme: {
light: 'vs',
dark: 'vs-dark',
},
}
})
Custom Themes
import { defineMonacoSetup } from '@slidev/types'
export default defineMonacoSetup((monaco) => {
// Define custom theme
monaco.editor.defineTheme('my-theme', {
base: 'vs-dark',
inherit: true,
rules: [
{ token: 'comment', foreground: '6A9955' },
{ token: 'keyword', foreground: 'C586C0' },
],
colors: {
'editor.background': '#1a1a2e',
},
})
return {
theme: {
dark: 'my-theme',
light: 'vs',
},
}
})
Type Definitions
Adding Types for Libraries
// setup/monaco.ts
import { defineMonacoSetup } from '@slidev/types'
export default defineMonacoSetup(async (monaco) => {
// Add React types
const reactTypes = await fetch(
'https://unpkg.com/@types/react/index.d.ts'
).then(r => r.text())
monaco.languages.typescript.typescriptDefaults.addExtraLib(
reactTypes,
'file:///node_modules/@types/react/index.d.ts'
)
})
Inline Type Definitions
```typescript {monaco}
// Types defined inline
interface Todo {
id: number
text: string
completed: boolean
}
const todos: Todo[] = [
{ id: 1, text: 'Learn Slidev', completed: true },
{ id: 2, text: 'Create presentation', completed: false },
]
```
Interactive Examples
Counter Demo
```typescript {monaco-run}
// Interactive counter
let count = 0
function increment() {
count++
console.log(`Count: ${count}`)
}
// Click Run multiple times!
increment()
```
API Simulation
```typescript {monaco-run}
// Simulated API call
async function fetchUser(id: number) {
// Simulate network delay
await new Promise(r => setTimeout(r, 500))
return {
id,
name: 'John Doe',
email: 'john@example.com'
}
}
const user = await fetchUser(1)
console.log(user)
```
Algorithm Visualization
```typescript {monaco-run}
// Bubble sort with steps
function bubbleSort(arr: number[]) {
const result = [...arr]
const steps: string[] = []
for (let i = 0; i < result.length; i++) {
for (let j = 0; j < result.length - i - 1; j++) {
if (result[j] > result[j + 1]) {
[result[j], result[j + 1]] = [result[j + 1], result[j]]
steps.push(`Swap: [${result.join(', ')}]`)
}
}
}
return { result, steps }
}
const { result, steps } = bubbleSort([5, 3, 8, 4, 2])
console.log('Steps:', steps.length)
steps.forEach(s => console.log(s))
console.log('Final:', result)
```
Code Runner Patterns
Show Concept Then Let Edit
# Array Methods
```typescript {monaco-run}
const numbers = [1, 2, 3, 4, 5]
// Try changing the function!
const result = numbers
.filter(n => n % 2 === 0)
.map(n => n * 2)
console.log(result)
```
Try modifying the code to:
- Filter odd numbers
- Triple instead of double
Interactive Quiz
# Fix the Bug
```typescript {monaco-run}
// This code has a bug - can you fix it?
function reverseString(str: string) {
return str.split('').reserve().join('')
}
console.log(reverseString('hello'))
// Expected: 'olleh'
```
Live Data Manipulation
```typescript {monaco-run}
const data = [
{ name: 'Alice', score: 85 },
{ name: 'Bob', score: 92 },
{ name: 'Charlie', score: 78 },
]
// Calculate statistics
const average = data.reduce((sum, d) => sum + d.score, 0) / data.length
const highest = Math.max(...data.map(d => d.score))
const passing = data.filter(d => d.score >= 80)
console.log(`Average: ${average.toFixed(1)}`)
console.log(`Highest: ${highest}`)
console.log(`Passing: ${passing.map(d => d.name).join(', ')}`)
```
Combining with Animations
Reveal Then Edit
<v-click>
```typescript {monaco}
// Code appears on click, then is editable
function greet(name: string) {
return `Hello, ${name}!`
}
```
</v-click>
Step-by-Step with Monaco
<v-clicks>
Start with this code:
```typescript {monaco}
const x = 1
```
Then try adding more lines!
</v-clicks>
Best Practices
1. Keep Examples Focused
```typescript {monaco-run}
// GOOD: Single concept
const sum = [1, 2, 3].reduce((a, b) => a + b, 0)
console.log(sum) // 6
```
2. Provide Starting Point
```typescript {monaco-run}
// Complete the function:
function capitalize(str: string): string {
// Your code here
return str
}
console.log(capitalize('hello')) // Should print: 'Hello'
```
3. Show Expected Output
```typescript {monaco-run}
// Code example
const result = [1, 2, 3].map(n => n ** 2)
console.log(result)
// Expected output: [1, 4, 9]
```
4. Handle Errors Gracefully
```typescript {monaco-run}
try {
const result = riskyOperation()
console.log(result)
} catch (error) {
console.error('Error:', error.message)
}
function riskyOperation() {
// Might throw an error
throw new Error('Oops!')
}
```
Limitations
- No DOM Access: Cannot manipulate the page DOM
- Limited APIs: Only standard JavaScript APIs available
- No Imports: Cannot import external packages
- Console Only: Output is console-based
Output Format
When creating Monaco code blocks:
PURPOSE: [What the code demonstrates]
INTERACTION: [How audience should interact]
CODE:
```[language] {monaco-run}
// Clear comments explaining purpose
[Code with good defaults]
// Expected output noted
SUGGESTED EDITS:
- Try changing X to Y
- Modify function to do Z