TypeScript Best Practices for Modern Development

TypeScript has become the standard for building robust JavaScript applications. Let's explore some best practices that will help you write better TypeScript code.

Use Strict Mode

Always enable strict mode in your tsconfig.json:

{
  "compilerOptions": {
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true
  }
}

Prefer Type Inference

Let TypeScript infer types when possible:

// Good - Type inferred
const message = "Hello, World!"
const count = 42

// Avoid - Unnecessary type annotation
const message: string = "Hello, World!"

Use Utility Types

TypeScript provides powerful utility types:

interface User {
  id: string
  name: string
  email: string
  age?: number
}

// Pick only needed properties
type UserPreview = Pick<User, "id" | "name">

// Make all properties optional
type PartialUser = Partial<User>

// Make all properties required
type RequiredUser = Required<User>

Discriminated Unions

Create type-safe state machines:

type LoadingState =
  | { status: "idle" }
  | { status: "loading" }
  | { status: "success"; data: string }
  | { status: "error"; error: Error }

function handleState(state: LoadingState) {
  switch (state.status) {
    case "idle":
      return "Not started"
    case "loading":
      return "Loading..."
    case "success":
      return state.data
    case "error":
      return state.error.message
  }
}

Avoid any

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

// Bad
function processData(data: any) {
  return data.value
}

// Good
function processData(data: unknown) {
  if (typeof data === "object" && data !== null && "value" in data) {
    return (data as { value: string }).value
  }
  return null
}

Conclusion

Following these TypeScript best practices will help you write more maintainable and type-safe code. Start implementing them in your projects today!