tsconfig cheatsheet for 2026.

Minimum modern tsconfig

{
  "compilerOptions": {
    "target": "ES2023",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "lib": ["ES2023"],
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "resolveJsonModule": true,
    "isolatedModules": true,
    "verbatimModuleSyntax": true,
    "noUncheckedIndexedAccess": true,
    "noImplicitOverride": true,
    "outDir": "dist",
    "rootDir": "src"
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist"]
}

strict family

"strict": true enables:

  • noImplicitAny
  • strictNullChecks
  • strictFunctionTypes
  • strictBindCallApply
  • strictPropertyInitialization
  • noImplicitThis
  • alwaysStrict
  • useUnknownInCatchVariables

Always start with strict.

Extra checks worth enabling

{
  "noUncheckedIndexedAccess": true,    // arr[0] is T | undefined
  "noImplicitOverride": true,          // require `override` keyword
  "noFallthroughCasesInSwitch": true,
  "noPropertyAccessFromIndexSignature": true,
  "exactOptionalPropertyTypes": true,
  "noUnusedLocals": true,
  "noUnusedParameters": true
}

target vs lib

  • target: JS version the emitted output uses (ES2023, etc).
  • lib: which built-in type declarations to include (DOM, ES2023, etc).

For Node:

{ "target": "ES2023", "lib": ["ES2023"] }

For browser:

{ "target": "ES2022", "lib": ["ES2022", "DOM", "DOM.Iterable"] }

module / moduleResolution (the confusing pair)

For pure Node ESM/CJS (2026):

{ "module": "NodeNext", "moduleResolution": "NodeNext" }

For bundlers (Vite/webpack/esbuild):

{ "module": "ESNext", "moduleResolution": "bundler" }

Never use "node" or "node16" for new projects — use NodeNext or bundler.

verbatimModuleSyntax

import type { User } from "./types";
import { fn } from "./mod";

Requires you to mark type-only imports. Clean and avoids round-tripping issues with ESM.

isolatedModules

Required for tools like swc/esbuild that compile files independently. Prevents const enum, untagged re-exports of types, etc.

Path aliases

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

import { foo } from "@/lib/foo";

Paths only affect type checking. Runtime needs tsconfig-paths, bundler config, or output rewriting.

Project references (monorepo)

// tsconfig.json
{
  "files": [],
  "references": [
    { "path": "packages/core" },
    { "path": "packages/web" }
  ]
}

// packages/core/tsconfig.json
{
  "compilerOptions": {
    "composite": true,
    "declaration": true,
    "outDir": "dist"
  }
}

tsc --build           # build all, in dependency order
tsc --build --watch

extends

{
  "extends": "@tsconfig/node20/tsconfig.json",
  "compilerOptions": {
    "outDir": "dist"
  }
}

Use community @tsconfig/* presets when you don’t want to manage from scratch.

JSX

{
  "jsx": "react-jsx",          // React 17+ classic transform
  "jsx": "preserve"            // for downstream bundler
}

Source maps

{
  "sourceMap": true,
  "declarationMap": true,
  "inlineSources": true
}

Always include sourcemaps in dev; toggle for prod.

Declaration files

{
  "declaration": true,         // emit .d.ts
  "emitDeclarationOnly": true, // ONLY emit types (let esbuild emit JS)
  "declarationMap": true
}

Output options

{
  "removeComments": false,
  "newLine": "lf",
  "preserveConstEnums": true,
  "importHelpers": true        // use tslib helpers
}

Files / include / exclude

{
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist", "**/*.test.ts"],
  "files": []                  // explicit list (rarely needed)
}

Common gotchas

  • target: ES5 is no longer needed — browsers ship ES2022.
  • module: CommonJS with ESM dependencies — interop nightmare.
  • strict: false “to make it work” — pay the type debt later instead.
  • skipLibCheck: false — slow CI; almost always want true.
  • paths without bundler config — works at type-check, fails at runtime.

CLI

tsc                          # build with tsconfig.json
tsc --noEmit                 # type-check only
tsc --watch
tsc --build packages/core
tsc --showConfig             # print resolved config

Read this next

If you want my strict tsconfig templates (lib, web, node), they’re at rajpoot.dev .

Building something AI-, backend-, or data-heavy and want a second pair of eyes? I do consulting and freelance work — see my projects and ways to reach me at rajpoot.dev .