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To install TypeScript definitions for Bun’s built-in APIs in your project, install @types/bun.
terminal
bun add -d @types/bun # dev dependency
Below is the full set of recommended compilerOptions for a Bun project. With this tsconfig.json, you can use top-level await, extensioned or extensionless imports, and JSX.
tsconfig.json
{
  "compilerOptions": {
    // Environment setup & latest features
    "lib": ["ESNext"],
    "target": "ESNext",
    "module": "Preserve",
    "moduleDetection": "force",
    "jsx": "react-jsx",
    "allowJs": true,
    "types": ["bun"],

    // Bundler mode
    "moduleResolution": "bundler",
    "allowImportingTsExtensions": true,
    "verbatimModuleSyntax": true,
    "noEmit": true,

    // Best practices
    "strict": true,
    "skipLibCheck": true,
    "noFallthroughCasesInSwitch": true,
    "noUncheckedIndexedAccess": true,
    "noImplicitOverride": true,

    // Some stricter flags (disabled by default)
    "noUnusedLocals": false,
    "noUnusedParameters": false,
    "noPropertyAccessFromIndexSignature": false
  }
}
If you’re using TypeScript 6.0 or later, you’ll also need to add "types": ["bun"] to your compilerOptions. See TypeScript 6 and 7 for details.
Refer to Ecosystem > TypeScript for a complete guide to TypeScript support in Bun.