Enums in Javascript with ES6

Is there a problem with this formulation?

I don’t see any.

Is there a better way?

I’d collapse the two statements into one:

const Colors = Object.freeze({
    RED:   Symbol("red"),
    BLUE:  Symbol("blue"),
    GREEN: Symbol("green")
});

If you don’t like the boilerplate, like the repeated Symbol calls, you can of course also write a helper function makeEnum that creates the same thing from a list of names.