Recommended config

strict Mode

syntax

// tsconfig.json
{ "compilerOptions": { "strict": true } }

example

// strict: true enables ALL of these at once:
// - strictNullChecks: null/undefined not assignable to other types
// - strictFunctionTypes: contravariant function parameter checking
// - strictBindCallApply: type-check bind, call, apply
// - strictPropertyInitialization: class props must be initialized
// - noImplicitAny: error on implicit any
// - noImplicitThis: error on 'this' with implicit any type
// - useUnknownInCatchVariables: catch variable is unknown, not any
// - alwaysStrict: emit "use strict" in every file

output

// strict: true is the recommended baseline for all new projects

Note Always start new projects with strict: true. You can selectively disable individual checks if needed (e.g., "strictPropertyInitialization": false) while keeping the rest. Enabling strict on a large existing JS-to-TS migration can produce thousands of errors — enable checks incrementally in that case.

Essential Compiler Options

TS · Configuration

syntax

// tsconfig.json compilerOptions

example

{
  "compilerOptions": {
    "strict": true,
    "target": "ES2022",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "resolveJsonModule": true,
    "allowImportingTsExtensions": true,
    "noEmit": true,
    "jsx": "react-jsx",
    "lib": ["ES2022", "DOM", "DOM.Iterable"]
  },
  "include": ["src"]
}

output

// A solid starting tsconfig for a modern bundled web app

Note moduleResolution: "bundler" (TS 5.0+) matches how Vite/webpack/esbuild resolve modules — it supports exports maps, .ts extensions in imports, and does not require file extensions. skipLibCheck: true speeds up compilation by not checking node_modules .d.ts files (only your code is checked).

TSTypeScript