Mini enum-like solution. Probably not all that useful;

enum.babel.js

import { invert, assign, object } from 'lodash';

class Enum {
    
  // Should probably look into using a Symbol for this instead?? 
	static privateKey = '_private';

	constructor(map) {
		const inverted = invert(map);
		const keys = Object.keys(map);
		
		this[Enum.privateKey] = { map, inverted, keys };

		assign(this, object(keys.map((k, i) => [k, i + 1])));
	}

	getForIndex(idx) {
		return this.getPrivate().keys[idx - 1];
	}

	isValidKey(index) {
		return typeof this.getForIndex(index) !== 'undefined';
	}

	value(index) {
		return this.getPrivate().map[this.getForIndex(index)];
	}

	getPrivate() {
		return this[Enum.privateKey];
	}
}

usage.babel.js

const enum = new Enum({ OPT_ONE : 'one', OPT_TWO : 'two', OPT_THREE : 'three' });

enum.isValidKey(enum.OPT_ONE); // true
enum.value(enum.OPT_ONE); // 'one'

enum.isValidKey(enum.foo); // false
enum.value(enum.foo); // undefined

enum.OPT_ONE; // 1
enum.OPT_TWO; // 2
enum.OPT_THREE; // 3