Enums in Typescript

Enums in TypeScript are a way to define a set of named constants.

Enums allow you to define a set of named constants. They are useful when you have a fixed set of values that are related to each other.

Example

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

// Usage
let direction: Direction = Direction.Up;
console.log(direction); // UP

In the example above, we define an enum Direction with four named constants Up, Down, Left, and Right. Each constant has an associated value.

Enums in TypeScript are similar to enums in other programming languages like C# or Java. However, TypeScript enums are more flexible and can have string values, whereas enums in other languages are limited to integer values.

Example: Enum as a Type

Enums can also be used as a type in TypeScript. For example, you can define a function that takes an enum value as an argument:

function move(direction: Direction) {
  console.log(`Moving ${direction}`);
}

move(Direction.Left); // Moving LEFT

Example: Check User Access

enum UserRole {
  ADMIN = "Admin",
  EDITOR = "Editor",
  VIEWER = "Viewer",
}

function checkAccess(role: UserRole): void {
  if (role === UserRole.ADMIN) {
    console.log("You have full access!");
  } else {
    console.log("Limited access only.");
  }
}

checkAccess(UserRole.ADMIN); // You have full access!

Summary

• Use Enums when you have a fixed set of related constants that represent different values
• Use cases: Status codes, User roles/permissions, Configuration options, Application states and etc.