What are ’enums’ in TypeScript and how can you use them? — TypeScript Interview Question #10

’Enums’ in TypeScript is a feature that allows you to define a named set of constant values, typically to represent a collection of related items or categories. Enums can make your code more understandable and less error-prone by providing a way to use symbolic names rather than raw values, such as integers or strings, directly.

There are two main types of enums in TypeScript: numeric enums and string enums.

1. Numeric enums:

By default, numeric enums will have their members’ values auto-incremented from 0. You can also explicitly set the initial value or assign specific values to each member.

Example:

enum DaysOfWeek {
  Sunday,    // 0
  Monday,    // 1
  Tuesday,   // 2
  Wednesday, // 3
  Thursday,  // 4
  Friday,    // 5
  Saturday   // 6
}

Usage:

const today: DaysOfWeek = DaysOfWeek.Friday;
console.log(today); // 5

2. String enums:

These Enums allow you to use string values instead of numeric values.

Example:

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

Usage:

const move: Directions = Directions.Left;
console.log(move); // "LEFT"

Enums in TypeScript are a feature that allows you to define a named set of constant values, typically to represent a collection of related items or categories. Enums can make your code more understandable and less error-prone by providing a way to use symbolic names rather than raw values, such as integers or strings, directly.

There are two main types of enums in TypeScript: numeric enums and string enums.

1. Numeric enums:

By default, numeric enums will have their members’ values auto-incremented from 0. You can also explicitly set the initial value or assign specific values to each member.

Example:

enum DaysOfWeek {
  Sunday,    // 0
  Monday,    // 1
  Tuesday,   // 2
  Wednesday, // 3
  Thursday,  // 4
  Friday,    // 5
  Saturday   // 6
}

Usage:

const today: DaysOfWeek = DaysOfWeek.Friday;
console.log(today); // 5

2. String enums:

These enums allow you to use string values instead of numeric values.

Example:

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

Usage:

const move: Directions = Directions.Left;
console.log(move); // "LEFT"