Private methods and accessors

Category: JavaScript
Type: New or changed feature
Status: Enabled by default (Chrome 84)
Intent stage: Prepare to ship

Summary

Keeping state and behavior private to a class lets library authors present a clear, stable interface, while changing their code over time behind the scenes. The class fields proposal provides private fields for classes and instances, and this proposal builds on that by adding private methods and accessors (getter/setters) to JavaScript. With this proposal, any class element can be private.

Motivation

https://v8.dev/features/class-fields https://github.com/tc39/proposal-private-methods/blob/master/README.md

Standards & signals

Specification: https://tc39.es/proposal-private-methods/
Firefox: Positive — See also https://bugzilla.mozilla.org/show_bug.cgi?id=1435826
Safari: In development — Also https://bugs.webkit.org/show_bug.cgi?id=194435
Web developers: Mixed signals
Tracking bug: https://bugs.chromium.org/p/v8/issues/detail?id=8330

Docs: https://docs.google.com/document/d/1T-Ql6HOIH2U_8YjWkwK2rTfywwb7b3Qe8d3jkz72KwA/edit

Explainers: https://v8.dev/features/class-fields https://github.com/tc39/proposal-private-methods/blob/master/README.md

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