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TS Enums

Enums in TypeScript are a way to define a set of named constants. Enums make it easier to manage and use sets of related values in a type-safe manner.

Key Topics

Numeric Enums

Numeric enums assign a numeric value to each member. By default, values start at 0 and increment automatically.

enum Direction {
    North,
    East,
    South,
    West
}

console.log(Direction.North); // 0
console.log(Direction.South); // 2

Output

0

2

Explanation: The enum Direction assigns North = 0, East = 1, South = 2, and West = 3.

String Enums

String enums assign string values to each member, offering better readability.

enum Status {
    Active = "ACTIVE",
    Inactive = "INACTIVE",
    Pending = "PENDING"
}

console.log(Status.Active); // "ACTIVE"
console.log(Status.Pending); // "PENDING"

Output

ACTIVE

PENDING

Explanation: The enum Status explicitly maps each member to a string value for better readability and comparison.

Heterogeneous Enums

Heterogeneous enums allow a mix of string and numeric values for members. Use these sparingly for specific use cases.

enum MixedEnum {
    Yes = "YES",
    No = 0
}

console.log(MixedEnum.Yes); // "YES"
console.log(MixedEnum.No);  // 0

Output

YES

0

Explanation: The enum MixedEnum contains a string member Yes and a numeric member No, demonstrating a combination of value types.

Key Takeaways

  • Numeric Enums: Use for sequential values starting from 0 by default.
  • String Enums: Offer better readability and are ideal for descriptive constants.
  • Heterogeneous Enums: Mix value types for specialized use cases but avoid overuse.
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