How does Vite support TypeScript? How to configure type checking?

Vite provides comprehensive TypeScript support, allowing developers to seamlessly use TypeScript in Vite projects. Here's how to use and configure TypeScript in Vite:

Basic Support:

Vite supports TypeScript out of the box without additional configuration. You can directly use .ts and .tsx files, and Vite will automatically handle type checking and transpilation.

Configuration Files:

1. tsconfig.json: TypeScript configuration file
2. vite.config.ts: Vite configuration file (TypeScript version)

Type Checking:

Development Environment:

• Vite doesn't perform type checking by default to maintain fast development experience
• Can implement type checking via vite-plugin-checker plugin
• Or run tsc --noEmit in a separate process

Production Build:

• Vite uses esbuild for transpilation during build
• esbuild's type checking capabilities are limited, recommend running tsc in CI/CD

Configuration Example:

json
// tsconfig.json
{
  "compilerOptions": {
    "target": "ES2020",
    "useDefineForClassFields": true,
    "module": "ESNext",
    "lib": ["ES2020", "DOM", "DOM.Iterable"],
    "skipLibCheck": true,
    "moduleResolution": "bundler",
    "allowImportingTsExtensions": true,
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "react-jsx",
    "strict": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noFallthroughCasesInSwitch": true
  },
  "include": ["src"],
  "references": [{ "path": "./tsconfig.node.json" }]
}

Path Aliases:

typescript
// vite.config.ts
import { defineConfig } from 'vite'
import path from 'path'

export default defineConfig({
  resolve: {
    alias: {
      '@': path.resolve(__dirname, './src')
    }
  }
})

json
// tsconfig.json
{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "@/*": ["src/*"]
    }
  }
}

Environment Variable Type Definitions:

typescript
// src/vite-env.d.ts
interface ImportMetaEnv {
  readonly VITE_API_URL: string
  readonly VITE_APP_TITLE: string
}

interface ImportMeta {
  readonly env: ImportMetaEnv
}

Type Checking Plugin:

typescript
// vite.config.ts
import { defineConfig } from 'vite'
import checker from 'vite-plugin-checker'

export default defineConfig({
  plugins: [
    checker({
      typescript: true,
      eslint: {
        lintCommand: 'eslint "./src/**/*.{ts,tsx}"'
      }
    })
  ]
})

Best Practices:

1. Use vite-plugin-checker for real-time type checking in development
2. Run tsc --noEmit in CI/CD pipeline to ensure type safety
3. Enable all strict type checking with strict mode
4. Configure skipLibCheck appropriately to improve build speed
5. Define types for environment variables to avoid type errors