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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2 Comments

arve Over a year ago

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?

fazlu Over a year ago

make constants.js file in your project and put this into file like this export const WeekDays

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

4

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);

answered May 18, 2020 at 10:27

Eugene Obrezkov

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Comments

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

1

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);

answered May 17, 2020 at 22:24

Olian04

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2 Comments

arve Over a year ago

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?

Olian04 Over a year ago

@arve you'll have to export the "enum", then you can import it in other files. See CommonJS: flaviocopes.com/commonjs

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

0

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

answered Apr 4, 2022 at 14:01

Dave Lee

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