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Enums

Enums are a set of defined constants. The simplest form of enum is a numeric enum:

enum Direction {
  North, // 0
  East, // 1
  South, // 2
  West, // 3
}

let myDirection: Direction = Direction.North;
console.log(myDirection); // Outputs: 0

The killer feature of enums is that in your code you can have nicely named identifiers like Direction.North, and under the hood you can have simple unique values, like 0. Typescript automatically increments the underlying values for us as we define new enums.

You can also explicitly set the values, and TypeScript will ensure they're unique:

enum StatusCode {
  OK = 200,
  Created = 201,
  BadRequest = 400,
  Unauthorized = 401,
  NotFound = 404,
}

Bidirectional Mapping

Numeric enums are bidirectional, which just means you can easily convert from the underlying value to the name and vice versa:

const directionValue: number = Direction.South;
// 2
const directionName: string = Direction[directionValue];
// "South"

Assignment

Support.ai has an internal system that calculates the severity of customer support requests, so that they can prioritize the most important requests first.

Create and export an enum named RequestSeverity, the enum members should be in order:
- Low
- Medium
- High
- Critical

Let TypeScript handle setting the unique values by default.

Complete the isCritical function. It should return true if the given SupportRequest's severity is equal to the enum's Critical value, and false otherwise.