Why doesn't SolidJS use virtual DOM? How does it achieve high performance?

SolidJS doesn't use virtual DOM, employing direct DOM manipulation and fine-grained update mechanisms:

How It Works:

1. Compile-time Optimization: Compiles JSX to efficient DOM creation and update code
2. Fine-grained Tracking: Each signal knows which DOM nodes depend on it
3. Direct Updates: Directly updates corresponding DOM nodes when state changes

Example Comparison:

javascript
// React - Virtual DOM diff
function Counter() {
  const [count, setCount] = useState(0);
  return <div>{count}</div>;
}
// Re-renders entire component on every update

// SolidJS - Fine-grained update
function Counter() {
  const [count, setCount] = createSignal(0);
  return <div>{count()}</div>;
}
// Only updates the text node corresponding to {count()}

Performance Advantages:

• No virtual DOM diff algorithm needed
• Avoids unnecessary DOM operations
• Smaller memory footprint
• Faster update speed

Implementation Mechanism:

• Uses createSignal to create reactive state
• Compiler transforms JSX to runtime functions like insert, createComponent
• Each expression is wrapped in reactive context
• Automatically establishes dependency between signals and DOM nodes

Use Cases:

• Large list rendering
• High-frequency update applications
• Scenarios requiring extreme performance