Private Fields proposal to form a single unified proposal here.
NOTE: This proposal has been merged with thePlease do not create new issues/PRs on this repo.
ES Class Fields & Static Properties
This presents two related proposals: "class instance fields" and "class static fields". "Class instance fields" describe properties intended to exist on instances of a class (and may optionally include initializer expressions for said properties). "Class static fields" are declarative properties that exist on the class object itself (and may optionally include initializer expressions for said properties).
Latest spec text: https://tc39.github.io/proposal-class-public-fields/