Should You Use Enum or Const in TypeScript? Key Differences and Best Practices

When working with TypeScript, one common question developers face is whether to use enum or const for defining a set of constant values. Both approaches have their use cases, advantages, and drawbacks. In this article, we’ll compare enum and const and help you decide which one to use in your TypeScript projects.

Understanding Enum in TypeScript

Enums are a feature in TypeScript that allows you to define a named set of constant values. They come in two main types: numeric and string enums.

Numeric Enum

enum Status {
  Pending,
  InProgress,
  Completed
}

console.log(Status.Pending); // Output: 0
console.log(Status[1]); // Output: 'InProgress'

By default, TypeScript assigns numeric values starting from 0, but you can explicitly set them as well:

enum Status {
  Pending = 1,
  InProgress = 2,
  Completed = 3
}

String Enum

enum Status {
  Pending = "PENDING",
  InProgress = "IN_PROGRESS",
  Completed = "COMPLETED"
}

String enums provide better readability and prevent accidental numeric errors.

Understanding Const in TypeScript

A const is a simple way to declare constants using TypeScript’s const keyword along with object literals or arrays.

const Status = {
  Pending: "PENDING",
  InProgress: "IN_PROGRESS",
  Completed: "COMPLETED"
} as const;

With as const, TypeScript treats the values as readonly, ensuring they cannot be changed later.

Enum vs Const: Key Differences

Performance Consideration

Enums generate additional JavaScript code, which can increase bundle size:

var Status;
(function (Status) {
    Status[Status["Pending"] = 0] = "Pending";
    Status[Status["InProgress"] = 1] = "InProgress"…