TypeScript Best Practices for 2025

TypeScript continues to evolve, and with it come new patterns and best practices. Let's explore some modern approaches to writing better TypeScript code.

Use Strict Mode

Always enable strict mode in your tsconfig.json:

{
  "compilerOptions": {
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "noImplicitOverride": true
  }
}

Prefer Type over Interface

While both work, type is more versatile:

// Good
type User = {
  id: string
  name: string
}

// Also good, but more limited
interface User {
  id: string
  name: string
}

Use Discriminated Unions

For handling different states or types:

type Result<T> =
  | { status: 'success'; data: T }
  | { status: 'error'; error: Error }
  | { status: 'loading' }

function handleResult<T>(result: Result<T>) {
  switch (result.status) {
    case 'success':
      console.log(result.data) // Type-safe!
      break
    case 'error':
      console.error(result.error)
      break
    case 'loading':
      console.log('Loading...')
      break
  }
}

Avoid any

Use unknown instead when you truly don't know the type:

// Bad
function processData(data: any) {
  return data.value // No type checking
}

// Good
function processData(data: unknown) {
  if (typeof data === 'object' && data !== null && 'value' in data) {
    return data.value
  }
  throw new Error('Invalid data')
}

Conclusion

Following these best practices will help you write more maintainable and type-safe TypeScript code. Keep learning and stay updated with the latest TypeScript features!