- Never use
any.
- In case there's no alternative, use
unknown (more about unknown).
- Use ReadOnly arrays to ensure there's no scope for mutation (unless mutation is needed).
const numbers: ReadonlyArray<number> = [1, 2, 3];
- Array generics over typecasting.
const numbers: Array<number>;
//instead of const numbers: any[];
- Use interfaces over types for better extensibility.
- TS util types:
interface Person {
name: string;
age: number;
address: string;
}
type PartialPerson = Partial<Person>; // Makes all properties optional
type PersonName = Pick<Person, 'name'>; // Extracts a subset of properties
type PersonWithoutAge = Omit<Person, 'age'>; // Removes a property
//For enums, we use Exclude
enum fruits {
"apple",
"orange",
"marshmellow".
"lemon"
}
type vitaminCFruits = Exclude<fruits, "apple">;
- Nullish coalescing operator over ternary operator at times.
const url = props.baseurl?props.baseurl:"";
//instead:
const url = props.baseurl ?? "";
- Always try to have function return type set:
async function sum(a: number, b: number): Promise<number> {...}
- Remember,
Promise.all is all-or-nothing. If any promise fails, the whole thing fails.
If you want all Promises to be proccessed (both resolved and failed), use Promise.allSettled().
