Configurare si setup

# Instalare globala (pentru CLI tsc)
npm install -g typescript

# Instalare in proiect (recomandat)
npm install -D typescript

# Verificare versiune
tsc --version    # Version 5.x.x

# Initializare tsconfig.json
tsc --init

Fisierul tsconfig.json controleaza comportamentul compilatorului TypeScript. Iata o configuratie moderna recomandata:

{
"compilerOptions": {
// Baza
"target": "ES2022",              // JavaScript target
"module": "NodeNext",            // Sistem module
"moduleResolution": "NodeNext",  // Rezolutie import-uri
"lib": ["ES2022"],               // API-uri disponibile

// Strictete (TOATE activate!)
"strict": true,                  // Activeaza tot ce urmeaza:
// "strictNullChecks": true,     // null/undefined trebuie gestionate
// "strictFunctionTypes": true,  // Parametri functii stricti
// "strictPropertyInitialization": true, // Proprietati initializate
// "noImplicitAny": true,        // Interzice any implicit
// "noImplicitThis": true,       // this trebuie tipizat

// Verificari suplimentare
"noUncheckedIndexedAccess": true, // array[i] poate fi undefined
"noUnusedLocals": true,           // Variabile nefolosite = eroare
"noUnusedParameters": true,       // Parametri nefolositi = eroare
"exactOptionalPropertyTypes": true, // Optional != undefined explicit
"noFallthroughCasesInSwitch": true, // switch fara break = eroare

// Output
"outDir": "./dist",              // Folder output
"rootDir": "./src",              // Folder sursa
"declaration": true,             // Genereaza .d.ts
"sourceMap": true,               // Source maps pentru debugging
"removeComments": true,          // Sterge comentarii din output

// Interoperabilitate
"esModuleInterop": true,         // Import default din CommonJS
"forceConsistentCasingInImports": true,
"skipLibCheck": true,            // Skip verificare .d.ts (viteza)
"resolveJsonModule": true        // Import JSON direct
},
"include": ["src/**/*"],
"exclude": ["node_modules", "dist", "**/*.test.ts"]
}

VS Code are suport nativ excelent pentru TypeScript. Extensii recomandate:

• TypeScript Importer - auto-import la completare
• Error Lens - erori afisate inline
• Pretty TypeScript Errors - erori formatate lizibil
• ESLint - linting cu reguli TypeScript

ESLint pentru TypeScript

npm install -D eslint @eslint/js typescript-eslint

// eslint.config.js
import eslint from '@eslint/js';
import tseslint from 'typescript-eslint';

export default tseslint.config(
eslint.configs.recommended,
...tseslint.configs.strictTypeChecked,
...tseslint.configs.stylisticTypeChecked,
{
languageOptions: {
parserOptions: {
projectService: true,
tsconfigRootDir: import.meta.dirname
}
},
rules: {
'@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
'@typescript-eslint/consistent-type-imports': 'error',
'@typescript-eslint/no-floating-promises': 'error'
}
}
);