tsconfig.json Configuration & Strict Mode

Best practices for strict compiler flags, path aliases, and module resolution

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The tsconfig.json file specifies the root files and compiler options required to compile your project. Enabling strict mode unlocks the maximum safety and reliability benefits of TypeScript.

The Power of "strict: true"

"strict": true: Turns on a suite of type-checking behaviors including noImplicitAny, strictNullChecks, strictFunctionTypes, and strictBindCallApply.

strictNullChecks: When enabled, null and undefined are distinct types and cannot be assigned to variables unless explicitly permitted via unions (string | null).

paths: Configures module aliases (e.g., "@/*": ["./src/*"]) so you can avoid messy relative imports like ../../components.

target: Specifies the output JavaScript ECMAScript version (e.g., "ES2022").

Production-Grade tsconfig.json

Try It Yourself »

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "lib": ["ES2022", "DOM"],
    "strict": true,
    "noImplicitAny": true,
    "strictNullChecks": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noFallthroughCasesInSwitch": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "baseUrl": ".",
    "paths": {
      "@/*": ["src/*"]
    }
  },
  "include": ["src/**/*"]
}

This configuration maximizes type safety and clean import ergonomics across the team.

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Test Yourself With Exercise

+15 XP

What compiler flag prevents null and undefined from being silently assigned to string or number types?

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