What about Magic strings?

Do you think that can be good to include something about magic strings?

Bad:

let posts = getPostsFromCategory('sports');

Good:

const categories = {
  sports: 'sports',
  economy: 'economy'
};

let posts = getPostsFromCategory(categories.sports);

[ryanmcdermott]

Keyboard keycodes are another example you see in the front-end JavaScript world, where you have something like:

const KEYCODES = {
  ENTER: 13
};

document.addEventListener('keydown', function(event) {
  if (event.which === KEYCODES.ENTER) {
    //...
  }
}

[ProLoser]

This is typically how I do things. I’ll also go a step further and add enums statically to my classes for more organized namespacing (rather than just having randomly floating constant objects).

export default class Person { /* ... */ }

// Static Property:
Person.GENDERS = {
  MALE: 'm',
  FEMALE: 'f',
  OTHER: 'na'
};

// Const + Static Property:
const GENDERS = { ... };
Person.GENDERS = GENDERS;

// New Syntax Static Property:
class Person {
  static const GENDERS = { ... };
}

// Static Property Usage:
import Person from './Person';
let bob = new Person();
bob.setGender( Person.GENDERS.MALE );

// Or you can do a Named Export Variation:
import Person, { GENDERS } from './Person'; // or { GENDERS as PERSON_GENDERS }
let bob = new Person();
bob.setGender( GENDERS.MALE );

This allows me to keep the enums very close to their intended usage. And it’s easier to expose since I don’t have to go around creating some unrelated global / flat constants container object. person.gender can be one of Person.GENDERS in essence.