How to develop a Vite plugin? What are the common hook functions?

Vite provides a rich plugin system that allows developers to extend Vite's functionality. Here are the key points of Vite plugin development:

Basic Plugin Structure:

A Vite plugin is an object containing a name property and various hook functions:

javascript
export default function myPlugin() {
  return {
    name: 'my-plugin',
    // Hook functions
    config(config) {
      // Modify configuration
    },
    resolveId(source) {
      // Resolve module ID
    },
    load(id) {
      // Load module content
    },
    transform(code, id) {
      // Transform code
    }
  }
}

Common Hook Functions:

1. config: Modify Vite configuration, called after config resolution
2. configResolved: Called after configuration is resolved
3. configureServer: Configure dev server, can add middleware
4. resolveId: Custom module resolution logic
5. load: Custom module loading logic
6. transform: Transform code content (most commonly used)
7. buildStart/buildEnd: Called at build start/end
8. generateBundle: Called when generating bundle

Rollup Plugin Compatibility:

Vite plugins are compatible with Rollup plugins. Most Rollup plugins can be used directly in Vite. However, note:

• Vite plugins run in both development and production environments
• Some Rollup-specific hooks only work in production

Development Environment Specific Hooks:

• handleHotUpdate: Custom HMR update logic
• configureServer: Configure dev server
• transformIndexHtml: Transform HTML files

Plugin Example:

javascript
export default function myTransformPlugin() {
  return {
    name: 'my-transform',
    transform(code, id) {
      if (id.endsWith('.js')) {
        return code.replace(/foo/g, 'bar')
      }
    }
  }
}

Plugin Configuration:

Use plugins in vite.config.js:

javascript
import myPlugin from './my-plugin'

export default {
  plugins: [myPlugin()]
}

Best Practices:

• Plugins should have clear naming and documentation
• Use enforce option to control plugin execution order (pre, post)
• Only process target files, avoid unnecessary transformations
• Provide reasonable default configurations and options