how to create enum values with es6 in node js?

Question

Is it possible to create enum values in JavaScript and assign them to integer values, similar to other languages. For example in C#, I declare an enum in the following way:

enum WeekDays { Monday = 0, Tuesday =1, Wednesday = 2, Thursday = 3, Friday = 4, Saturday =5, Sunday = 6 }

fazlu · Accepted Answer · 2020-05-17 22:27:35Z

7

You can use object as an enum after freezing it like example below:

const WeekDays = Object.freeze({ Monday: 0, Tuesday: 1, Wednesday: 2, Thursday: 3, Friday: 4, Saturday: 5, Sunday: 6 })

answered May 17, 2020 at 22:27

fazlu

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thanks, sorry i'm new to javascript, why do we use object.freeze and how can i put this in a file and use it in different parts of my application.when reading integer values from database, how can i convert it back to enum values?
– arve
CommentedMay 17, 2020 at 22:38
make constants.js file in your project and put this into file like this export const WeekDays
– fazlu
CommentedMay 17, 2020 at 22:46

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Eugene Obrezkov · Accepted Answer · 2020-05-18 10:27:24Z

You can create a simple object and export it via module.exports:

// days.js module.exports = { Monday: 0, Tuesday: 1, Wednesday: 2, Thursday: 3, Friday: 4, Saturday: 5, Sunday: 6 } // file-where-you-want-to-use.js const DAYS = require('./days.js'); console.log(DAYS.Monday);

Olian04 · Accepted Answer · 2020-05-17 22:24:38Z

You can use a plain old object:

const WeekDays = { Monday: 0, Tuesday: 1, Wednesday: 2, Thursday: 3, Friday: 4, Saturday: 5, Sunday: 6 } const day1 = WeekDays.Monday; const day2 = WeekDays.Tuesday; console.log(day1, day2, day1 === day2); console.log(day1 === WeekDays.Monday, day2 === WeekDays.Tuesday);

thanks, I want to have this enum available through all my application. so if I put this in its own file, enum.js, how can use the weekdays in other files? — arve, CommentedMay 17, 2020 at 22:34
@arve you'll have to export the "enum", then you can import it in other files. See CommonJS: flaviocopes.com/commonjs — Olian04, CommentedMay 17, 2020 at 23:52

Dave Lee · Accepted Answer · 2022-04-04 14:01:36Z

To add some sort of variables that you'd like to use:

// days.js module.exports = { Monday: 0, Tuesday: 1, Wednesday: 2, Thursday: 3, Friday: 4, Saturday: 5, Sunday: 6 } // file-where-you-want-to-use.js const DAYS = require('./days.js'); const firstDayOfWeek = 'Monday'; console.log((DAYS)[firstDayOfWeek]); // 0

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