Mappings for enums in typescript

1-EnumMap.ts

export class EnumMap<E, T> {
	values: string[];
	enum_: E;

	private constructor(enum_: E, mappings: EnumMap.Type<E, T>) {
		this.values = Object.keys(mappings);
		this.enum_ = enum_;
		return Object.assign(Object.create(this), mappings);
	}

	static of<E, T>(enum_: E, mappings: EnumMap.Type<E, T>): EnumMap<E, T> & EnumMap.Type<E, T> {
		return new EnumMap<E, T>(enum_, mappings) as (EnumMap<E, T> & EnumMap.Type<E, T>);
	}
}

export namespace EnumMap {
	export type Type<E, T> = { [P in keyof E]: T; };
}

2-usage.ts

enum Size {
	Small, Medium, Large
}

// one mapping to string
const SizeView = EnumMap.of(Size, {
	Small: 's',
	Medium: 'm',
	Large: 'l'
});

class PantsMeasure {
	constructor(public waist: number,
				public hips: number,
				public rise: number,
				public inseam: number,
				public cuff: number) {
	}
}

// a second mapping, now to PantsMeasure
const SizePantsMeasure = EnumMap.of(Size, {
	Small: new PantsMeasure(...),
	Medium: new PantsMeasure(...),
	Large: new PantsMeasure(...)
});

3-results.ts

SizeView.Small == 's'
SizePantsMeasure.Small == PantsMeasure(...)

SizeView.values == Object.keys(SizeView) == SizePantsMeasure.values == Object.keys(SizePantsMeasure) == ['Small', 'Medium', 'Large']

SizeView.enum_ === SizePantsMeasure.enum_ === Size

notes.ts

enum E {
  A, B
}


type KeysAB = { [P in keyof typeof E] };
type Keys01 = { [P in E] };