@js-bits/enumerate

Easy to use, Symbol-based enum implementation

Just list values you need and enumerate tag function will create an object with corresponding keys and unique values for your convenience.

Installation

Install with npm:

npm install @js-bits/enumerate

Install with yarn:

yarn add @js-bits/enumerate

Import where you need it:

import enumerate from '@js-bits/enumerate';

or require for CommonJS:

const enumerate = require('@js-bits/enumerate');

How to use

Example 1:

const { FOOT, METER } = enumerate`FOOT METER`;

const convertToFeet = (value, unit = FOOT) => {
  if (unit === METER) {
    return value * 3.281;
  }
  return value;
};

console.log(`${convertToFeet(5)} feet`); // 5 feet
console.log(`${convertToFeet(2, METER)} feet`); // 6.562 feet

Example 2:

const STAR_WARS = enumerate`I II III IV V VI`;

const getEpisodeName = episode => {
  const { I, II, III, IV, V, VI } = STAR_WARS;
  switch (episode) {
    case I:
      return 'The Phantom Menace';
    case II:
      return 'Attack of the Clones';
    case III:
      return 'Revenge of the Sith';
    case IV:
      return 'A New Hope';
    case V:
      return 'The Empire Strikes Back';
    case VI:
      return 'Return of the Jedi';
    default:
      return 'Unknown';
  }
};

console.log(getEpisodeName(STAR_WARS.III)); // Revenge of the Sith
console.log(getEpisodeName(STAR_WARS.IV)); // A New Hope
console.log(getEpisodeName(STAR_WARS.X)); // Error: Invalid enum key: X

Primitive values

By default enumerate converts values to Symbols:

console.log(enumerate`FOOT METER`); // { FOOT: Symbol(FOOT), METER: Symbol(METER) }

You can change this behavior by specifying an appropriate converter:

console.log(enumerate(String)`FOOT METER`); // { FOOT: 'FOOT', METER: 'METER' }
console.log(enumerate(Number)`ZERO ONE TWO`); // { ZERO: 0, ONE: 1, TWO: 2 }
// or
const enumString = enumerate(String);
const enumNumber = enumerate(Number);
console.log(enumString`FOOT METER`); // { FOOT: 'FOOT', METER: 'METER' }
console.log(enumNumber`ZERO ONE TWO`); // { ZERO: 0, ONE: 1, TWO: 2 }

Or you can implement your custom converter:

const enum10s = enumerate((acc, item) => {
  acc[item] = (Object.keys(acc).length + 1) * 10;
  return acc;
});

console.log(enum10s`
  CODE1
  CODE2
  CODE3
`); // { CODE1: 10, CODE2: 20, CODE3: 30 }

But remember that only default behavior guarantees global uniqueness of enumerated values.

Notes

• Be careful adding new items to an existing numeric enum. Always append them to the end of the list to avoid changing previous item values.
• Does not include any polyfills, which means that Internet Explorer is not supported.