Sometimes we want immutable enums in Javascript, but standard objects are not really ideal for this, and can be accidentally modified.

Enum.js solves this problem by providing a factory function to generate immutable enums (where possible in the browser). If a browser does not support the methods used, then Enum.js will fall back to using mutable objects.

Using Enum.js is quite simple:

var Enum = require('enum');
var MyEnum = new Enum('First Value', 'Second', 'thirdVal', '4');

This will give you an object with the following key-value pairings:

MyEnum.FIRST_VALUE; // 1
MyEnum.SECOND;      // 2
MyEnum.THIRD_VAL;   // 3
MyEnum[4];	        // 4

Enum.js automatically underscores and capitalises the entire key, to make sure it's standard.

If you should try to specify a key twice, Enum.js will only use the first instance of it.