node package manager
Loosely couple your services. Use Orgs to version and reuse your code. Create a free org »

enumify

Enumify

A JavaScript library for enums. To be used by transpiled ES6 (e.g. via Babel).

The approach taken by Enumify is heavily inspired by Java enums.

The basics

Install:

npm install enumify

Use:

import {Enum} from 'enumify';
 
class Color extends Enum {}
Color.initEnum(['RED', 'GREEN', 'BLUE']);
 
console.log(Color.RED); // Color.RED 
console.log(Color.GREEN instanceof Color); // true 
 
new Color();
    // Error: Enum classes can’t be instantiated 

Properties of enum classes

Enums get a static property enumValues, which contains an Array with all enum values:

for (const c of Color.enumValues) {
    console.log(c);
}
// Output: 
// Color.RED 
// Color.GREEN 
// Color.BLUE 

The inherited tool method enumValueOf() maps names to values:

console.log(Color.enumValueOf('RED') === Color.RED); // true 
true

Properties of enum values

Enumify adds two properties to every enum value:

  • name: the name of the enum value.

    > Color.BLUE.name
    'BLUE'
  • ordinal: the position of the enum value within the Array enumValues.

    > Color.BLUE.ordinal
    2

Adding properties to enum values

initEnum() also accepts an object as its parameter. That enables you to add properties to enum values:

class TicTacToeColor extends Enum {}
 
// Alas, data properties don’t work, because the enum 
// values (TicTacToeColor.X etc.) don’t exist when 
// the object literals are evaluated. 
TicTacToeColor.initEnum({
    O: {
        get inverse() { return TicTacToeColor.X },
    },
    X: {
        get inverse() { return TicTacToeColor.O },
    },
});
 
console.log(TicTacToeColor.O.inverse); // TicTacToeColor.X 

More information

  • The directory test/ contains examples.