TypeScript

Using TypeScript with Bun, including type definitions and compiler options

To get TypeScript definitions for Bun’s built-in APIs, install @types/bun.

terminal

bun add -d @types/bun # dev dependency

You can now reference the Bun global in your TypeScript files without errors in your editor.

Suggested compilerOptions

Bun supports top-level await, JSX, and imports with .ts extensions, which TypeScript doesn’t allow by default. Use these compilerOptions in a Bun project so TypeScript doesn’t warn about those features.

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
  }
}

Running bun init in a new directory generates this tsconfig.json for you.

terminal

bun init

TypeScript 6 and 7

If you’re using TypeScript 6.0 or later, you also need "types": ["bun"] in your compilerOptions. See TypeScript 6 and 7.