easy-enums, by Winterwell/SoDash/Orla

Enum is a simple yet useful utility for safer code.

It makes a set of string constants, kind of like a Java enum. It has a nice concise constructor which takes a space-separated string. E.g.

let MyFruit = new Enum('APPLE BANANA');

gives you MyFruit.APPLE == 'APPLE', MyFruit.BANANA == 'BANANA'

Also, each of the constants has an isCONSTANT() function added, so you can write: MyFruit.isAPPLE(myvar) -- which has the advantage that it will create a noisy error if if myvar is invalid (e.g. it helps catch typos). isCONSTANT() allows falsy values, but an unrecognised non-false value indicates an error.

MyFruit.values holds the full list (and is frozen to keep it safe from edits).

MyFruit.has(thing) provides a boolean test, true if thing is a valid value.

MyFruit.assert(thing) is a convenience test: It will throw an error if thing is invalid. Returns thing if fine.

There is also a fail-fast way to access a constant: MyKind.$VALUE() is identical to MyKind.VALUE except that it will trigger an error if MyKind.VALUE does not exist.

Use-case: It's safer than just using strings for constants, especially around refactoring. It does use strings, because you want to work with json.