Enums

Ek enum named values ka ek fixed set define karta hai — jab bhi ek variable ko sirf ek chhote, known set of options mein se ek hona chahiye, jaise status ya direction, tab yeh useful hai.

enum Status {
  Pending,
  Active,
  Completed,
}

let current: Status = Status.Active;
console.log(current);
console.log(Status[current]);

1
Active

Default roop se, enum members 0 se number hote hain — Status.Pending 0 hai, Status.Active 1 hai, aur aise hi aage. Status[current] us number ko wapas uske naam tak lookup karta hai.

String enums

Ek string enum har member ko iske bajaye ek explicit string value deta hai, jo aksar zyada clear hota hai jab aap value ko kahin log ya serialize karte ho.

enum Direction {
  Up = "UP",
  Down = "DOWN",
  Left = "LEFT",
  Right = "RIGHT",
}

let move: Direction = Direction.Left;
console.log(move);

LEFT

Aage: classes aur objects — data aur behavior ko saath mein bundle karna, TypeScript ke access modifiers ke sath.