(free to read online)
Feature watch: ECMAScript 2021
This blog post tracks actual and potential features of ES2021. I will continually update it.
A word on ECMAScript versions
Note that since the TC39 process was instituted, the importance of ECMAScript versions has much decreased. What really matters now is what stage a proposed feature is in: Once it has reached stage 4, it can be used safely. But even then, you still have to check if your engines of choice support it.
Proposed ECMAScript 2021 features
Recall that every ECMAScript feature proposal goes through stages:
- Stage 4 means that a feature will be in the next release (or the one after that).
- Stage 3 means that a feature still has a chance of being included in the next release.
Stage 4 and part of ECMAScript spec draft
-
String.prototype.replaceAll(Peter Marshall, Jakob Gruber, Mathias Bynens) -
Promise.any()(Mathias Bynens, Kevin Gibbons, Sergey Rubanov) -
WeakRefs (Dean Tribble, Mark Miller, Till Schneidereit, Sathya Gunasekaran, Daniel Ehrenberg) [proposal]
-
Logical assignment operators (Justin Ridgewell, Hemanth HM)
-
Numeric separators (Sam Goto, Rick Waldron)
Candidate features (stage 3)
The following features are currently at stage 3:
-
Legacy RegExp features in JavaScript (Claude Pache) [proposal]
-
Private methods and getter/setters for JavaScript classes (Daniel Ehrenberg, Kevin Gibbons)
-
Class public instance fields & private instance fields (Daniel Ehrenberg, Jeff Morrison, Kevin Smith, Kevin Gibbons):
-
Class public static fields, private static methods, private getters/setters (Daniel Ehrenberg, Kevin Gibbons, Jeff Morrison, Kevin Smith, Shu-Yu Guo)
-
Hashbang grammar (Bradley Farias) [proposal]
-
Top-level
await(Myles Borins) -
RegExp match indices (Ron Buckton)
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Atomics.waitAsync(Lars Hansen, Shu-yu Guo) [proposal] -
.item()(Shu-yu Guo, Tab Atkins) -
Import assertions (Myles Borins, Sven Sauleau, Dan Clark, Daniel Ehrenberg) [proposal]
FAQ
What do the stages mean?
They refer to maturity stages of the so-called “TC39 process”. Check section “The TC39 process” in “JavaScript for impatient programmers” for more information.
How is [my favorite proposed feature] doing?
If you are wondering what stages various proposed features are in, consult the readme of the ECMA-262 GitHub repository.
Is there an official list of ECMAScript features?
Yes, the TC39 repo lists finished proposals and mentions in which ECMAScript versions they are introduced.
Free books on ES2020
The following books cover JavaScript up to and including ECMAScript 2020 (and will be updated once ECMAScript 2021 comes out):
Both books are free to read online.