enum (Enumerated Types)

This lesson covers enum, used to name and manage a fixed set of choices. It's for anyone searching "TypeScript enum usage."

enum is a way to group related constants under one name. It's used for a similar purpose to the literal types from the previous lesson, but because the value itself gets a name, the code's meaning is easier to convey.

The example defines enum Weekday { Mon, Tue, Wed, Thu, Fri, Sat, Sun }. Unless specified otherwise, Mon is automatically numbered 0, Tue is 1, and so on.

A common early mistake is forgetting that an enum's value is actually a number (or string) underneath. Weekday.Mon looks like a name, but keeping in mind it's really the number 0 underneath helps avoid confusion.

In real projects, enum gets used for things like "day of the week," "order status," or "permission level" — fields with a fixed set of possible values.