5 TypeScript Tips That Will Save You Hours

TypeScript has become the standard for writing type-safe JavaScript. But are you using it to its full potential?

1. Use unknown Instead of any

// Bad
function parse(data: any) {
  return JSON.parse(data);
}

// Good
function parse(data: unknown) {
  if (typeof data === 'string') {
    return JSON.parse(data);
  }
  throw new Error('Expected string');
}

2. Discriminated Unions

type Success = { status: 'success'; data: string };
type Error = { status: 'error'; error: string };

type Result = Success | Error;

function handleResult(result: Result) {
  if (result.status === 'success') {
    console.log(result.data); // TypeScript knows this exists!
  }
}

3. Utility Types to the Rescue

// Make specific properties optional
type PartialUser = Partial<User>;

// Pick specific properties
type UserEmail = Pick<User, 'email' | 'name'>;

// Omit specific properties
type CreateUser = Omit<User, 'id'>;

4. Type Guards

function isString(value: unknown): value is string {
  return typeof value === 'string';
}

function process(value: unknown) {
  if (isString(value)) {
    console.log(value.toUpperCase()); // TypeScript knows it's a string!
  }
}

5. Template Literal Types

type Color = 'red' | 'blue';
type Quantity = 'light' | 'dark';

type Shade = `${Quantity}-${Color}`;
// 'light-red' | 'light-blue' | 'dark-red' | 'dark-blue'

Bonus: Use Strict Mode

Always enable strict mode in tsconfig.json:

{
  "compilerOptions": {
    "strict": true
  }
}

This catches many common errors at compile time!

Conclusion

These tips will help you write safer, more maintainable TypeScript code. Start using them today and see the difference.

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