Heterogeneous Enums

Part of the Introduction To TypeScript section of Coddy's JavaScript journey — lesson 55 of 73.

ypeScript also supports heterogeneous enums - enums that contain a mix of both string and numeric members within the same declaration.

Here's how you can create a heterogeneous enum:

enum MixedEnum {
  No = 0,
  Yes = "YES",
  Maybe = 1
}

In this example, No and Maybe are numeric members, while Yes is a string member. TypeScript allows this flexibility, though it's important to note that heterogeneous enums are rarely used in practice.

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

Challenge

Easy

Create a heterogeneous enum named ResponseCode that mixes string and numeric values:

Success initialized to 200
Error initialized to "ERROR"
NotFound initialized to 404
Timeout initialized to "TIMEOUT"

Create a function named handleResponse that takes one parameter:

code of type ResponseCode

The function should:

Check the response code and print different messages based on the value
If the code is ResponseCode.Success, print "Request successful"
If the code is ResponseCode.Error, print "General error occurred"
If the code is ResponseCode.NotFound, print "Resource not found"
If the code is ResponseCode.Timeout, print "Request timed out"
Have a return type of void

Create four variables to demonstrate the enum values:

successCode of type ResponseCode and assign it ResponseCode.Success
errorCode of type ResponseCode and assign it ResponseCode.Error
notFoundCode of type ResponseCode and assign it ResponseCode.NotFound
timeoutCode of type ResponseCode and assign it ResponseCode.Timeout

Print the following outputs:

Print the value of successCode
Print the value of errorCode
Print the value of notFoundCode
Print the value of timeoutCode
Call handleResponse with ResponseCode.Success
Call handleResponse with errorCode
Call handleResponse with the numeric value 404

Cheat sheet

TypeScript supports heterogeneous enums that contain a mix of both string and numeric members within the same declaration:

enum MixedEnum {
  No = 0,
  Yes = "YES",
  Maybe = 1
}

In heterogeneous enums, you can mix numeric and string values. While TypeScript allows this flexibility, heterogeneous enums are rarely used in practice.

Try it yourself

// TODO: Write your code here

// Create the ResponseCode enum


// Create the handleResponse function


// Create the demonstration variables


// Print the required outputs

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

Heterogeneous Enums

Cheat sheet

All lessons in Introduction To TypeScript