Slidev Magic Move

Shiki Magic Move

This skill covers Shiki Magic Move, a powerful feature that creates smooth animated transitions between different code states, similar to Keynote's Magic Move effect.

When to Use This Skill

• Showing code evolution step by step
• Refactoring demonstrations
• Before/after code comparisons
• Tutorial walkthroughs
• Animated code transformations

How Magic Move Works

Magic Move analyzes two code blocks and: 1. Identifies unchanged tokens 2. Finds moved/renamed tokens 3. Detects added/removed tokens 4. Animates the transition smoothly

Basic Syntax

Use 4 backticks with md magic-move:

````markdown ```md magic-move

console.log('Hello')

console.log('Hello, World!')

``` ````

Each code block represents a step, animated on click.

Step-by-Step Example

Refactoring Journey

````markdown ```md magic-move

// Step 1: Original code
function add(a, b) {
  return a + b
}

// Step 2: Add types
function add(a: number, b: number) {
  return a + b
}

// Step 3: Add return type
function add(a: number, b: number): number {
  return a + b
}

// Step 4: Convert to arrow function
const add = (a: number, b: number): number => a + b

``` ````

Multiple Steps

````markdown ```md magic-move

const name = 'world'

const name = 'world'
const greeting = 'Hello'

const name = 'world'
const greeting = 'Hello'
console.log(`${greeting}, ${name}!`)

const name = 'world'
const greeting = 'Hello'
console.log(`${greeting}, ${name}!`)
// Output: Hello, world!

``` ````

Combining with Line Highlighting

Add highlights within Magic Move:

````markdown ``md magic-move {lines: true} ``js {*|1|2|3} const a = 1 const b = 2 const c = 3

const sum = 1 + 2 + 3

`````

Advanced Options

Control Animation Timing

````markdown ```md magic-move {at: 3}

// Starts at click 3
const x = 1

const x = 1
const y = 2

``` ````

Disable Line Numbers

````markdown ```md magic-move {lines: false}

const x = 1

const x = 2

``` ````

Combined Options

````markdown ``md magic-move {at: 2, lines: true} ``js {*|1|2} const first = 1 const second = 2

const result = first + second

`````

Real-World Examples

React Hook Evolution

````markdown ```md magic-move

// Class component state
class Counter extends React.Component {
  state = { count: 0 }

  increment = () => {
    this.setState({ count: this.state.count + 1 })
  }

  render() {
    return (
      <button onClick={this.increment}>
        {this.state.count}
      </button>
    )
  }
}

// Function component with useState
function Counter() {
  const [count, setCount] = useState(0)

  const increment = () => {
    setCount(count + 1)
  }

  return (
    <button onClick={increment}>
      {count}
    </button>
  )
}

// Simplified with inline handler
function Counter() {
  const [count, setCount] = useState(0)

  return (
    <button onClick={() => setCount(c => c + 1)}>
      {count}
    </button>
  )
}

``` ````

API Evolution

````markdown ```md magic-move

// Callbacks
function fetchUser(id, callback) {
  fetch(`/api/users/${id}`)
    .then(res => res.json())
    .then(data => callback(null, data))
    .catch(err => callback(err, null))
}

fetchUser(1, (err, user) => {
  if (err) console.error(err)
  else console.log(user)
})

// Promises
function fetchUser(id) {
  return fetch(`/api/users/${id}`)
    .then(res => res.json())
}

fetchUser(1)
  .then(user => console.log(user))
  .catch(err => console.error(err))

// Async/Await
async function fetchUser(id) {
  const res = await fetch(`/api/users/${id}`)
  return res.json()
}

try {
  const user = await fetchUser(1)
  console.log(user)
} catch (err) {
  console.error(err)
}

``` ````

Building a Function

````markdown ```md magic-move

function processData() {

}

function processData(data) {

}

function processData(data: string[]) {

}

function processData(data: string[]): string[] {
  return data
}

function processData(data: string[]): string[] {
  return data
    .filter(item => item.length > 0)
}

function processData(data: string[]): string[] {
  return data
    .filter(item => item.length > 0)
    .map(item => item.trim())
}

function processData(data: string[]): string[] {
  return data
    .filter(item => item.length > 0)
    .map(item => item.trim())
    .sort((a, b) => a.localeCompare(b))
}

``` ````

SQL Query Building

````markdown ```md magic-move

SELECT * FROM users

SELECT id, name, email FROM users

SELECT id, name, email FROM users
WHERE active = true

SELECT id, name, email FROM users
WHERE active = true
ORDER BY created_at DESC

SELECT id, name, email FROM users
WHERE active = true
ORDER BY created_at DESC
LIMIT 10

``` ````

Patterns and Tips

Start Simple, Add Complexity

````markdown ```md magic-move

// Start with the goal
const result = processData(input)

// Show the implementation
function processData(input) {
  return input
}

const result = processData(input)

// Add details
function processData(input) {
  return input
    .filter(x => x != null)
    .map(x => transform(x))
}

const result = processData(input)

``` ````

Show Problem Then Solution

````markdown ```md magic-move

// Problem: Callback hell
getData(function(a) {
  getMoreData(a, function(b) {
    getMoreData(b, function(c) {
      getMoreData(c, function(d) {
        // Finally done
      })
    })
  })
})

// Solution: Promises
getData()
  .then(a => getMoreData(a))
  .then(b => getMoreData(b))
  .then(c => getMoreData(c))
  .then(d => {
    // Clean and flat!
  })

``` ````

Highlight Changes with Comments

````markdown ```md magic-move

const config = {
  debug: true,
  timeout: 1000
}

const config = {
  debug: false,    // Changed!
  timeout: 1000
}

const config = {
  debug: false,
  timeout: 5000    // Increased!
}

``` ````

Best Practices

1. Small Steps: Each transition should show one logical change 2. Maintain Context: Keep surrounding code visible when possible 3. Use Comments: Add comments to explain what's changing 4. Consistent Style: Keep formatting consistent across steps 5. Test the Animation: Verify smooth transitions before presenting

Common Mistakes

❌ Too many changes at once

Step 1: Original code
Step 2: Completely different code

✓ Incremental changes

Step 1: Original
Step 2: Add one feature
Step 3: Add another feature
Step 4: Refactor

❌ Lost context

Step 1: function foo() { ... }
Step 2: const bar = ...  // Where did foo go?

✓ Preserved context

Step 1: function foo() { ... }
Step 2: function foo() { const bar = ... }

Interactive Playground

Try Magic Move at: https://shiki-magic-move.netlify.app/

Output Format

When creating Magic Move animations:

ANIMATION GOAL: [What transformation are you showing?]

STEPS:
1. [Initial state - describe]
2. [Change 1 - describe]
3. [Change 2 - describe]
...

CODE:

```[lang] [Step 1 code]

[Step 2 code]

...

SPEAKER NOTES:

• Step 1: [What to say]
• Step 2: [What to say]