Understanding Enums in Programming

In this Hasty Treat, Scott and Wes talk about enums in JS — what they are, what they do, and how they work in JavaScript.

LogRocket lets you replay what users do on your site, helping you reproduce bugs and fix issues faster. It’s an exception tracker, a session re-player and a performance monitor. Get 14 days free at logrocket.com/syntax.

03:11 - What are enums?

• A type restricting variables to one value from a predefined set of constants
• Direction = UP / DOWN / LEFT / RIGHT
• Role = ADMIN EDITOR AUTHOR VIEWER
• Day of the Week

05:12 - In GraphQL

• enum Role { ADMIN EDITOR AUTHOR VIEWER}
• Then

07:05 - In TypeScript

• First, declare the type:
  • enum direction = { UP, DOWN, LEFT, RIGHT }
• Then when you defined your function, use that type
  • type User { role: Role } or type User { role: [Role] }

08:49 - In JavaScript

• Not in JS yet
• There is a proposal in stage 1
  • https://github.com/rbuckton/proposal-enum
• And a babel plugin:
  • https://www.npmjs.com/package/babel-plugin-const-enum
• Can use case/switch
• Can use Object or Map keys

• Syntax 287: Hasty Treat - Records and Tuples in JavaScript

• Scott’s Instagram
• LevelUpTutorials Instagram
• Wes’ Instagram
• Wes’ Twitter
• Wes’ Facebook
• Scott’s Twitter
• Make sure to include @SyntaxFM in your tweets