ECMAScript 2016 to ES.Next support in Mozilla

This page needs to be updated to reflect current changes. (May 2019)

ECMAScript Next refers to new features of the ECMA-262 standard (commonly referred to as JavaScript) introduced after ECMAScript 2015. New versions of ECMAScript specifications are released yearly. So far, ES2016, ES2017, and ES2018 have been released. This year, the ES2019 specification will be released and ES2020 is the current ECMAScript draft specification.

You can see the latest proposals on the tc39/ecma262 GitHub repository.

A channel for feedback on ECMAScript standards is es-discuss.

Below is a list of features in ES2016+ and what version of Firefox they were implemented in.

ECMAScript 2016

ECMAScript 2017

ECMAScript 2018

ECMAScript 2019

ECMAScript 2020

This is the current ES.Next version.

Implemented proposals not in ES.Next

This section needs to be updated to reflect current changes. (May 2019)

The following features are already implemented, but only available in the Firefox Nightly channel and not yet included in a draft edition of an ECMAScript specification.

Additions to the ArrayBuffer object

New TypedObject objects

  • Based on Typed Objects draft, and exposed via a global TypedObject object, e.g. TypedObject.StructType & TypedObject.ArrayType. This feature is non-standard and not documented.

New Shared Memory objects

See also