实现的ES6类实现包括：
# TC39 接受的功能
# 其他供应商的利益
# 技术方面
原文地址可能需要翻墙，附原文如下：
Implement ES6 classes including:
- class declaration syntax
- enchancements to objects literal syntax
- ‘super’ keyword and Function.prototype.toMethod
The implementation will proceed in V8 under --harmony-classes flag.
Owners: Adam Klein (adamk@chromium.org), Erik Arvidsson (arv@chromium.org), Dmitry Lomov (dslomov@chromium.org)
# TC39 acceptance
Classes (in the form of compromise “maximally-minimal” classes) has been a part of ES6 for more than a year now. The complete spec has been in ES6 specification draft for quite a while.
At a July 2014 TC39 meeting some significant changes to instantiation semantics for classes were proposed, so the specification may still change in certain aspects.
However implementation of classes is a significant effort for V8, and critically important for Javascript community. It is critical that TC39 receives deep implementation feedback on the feature earlier than later. To mitigate spec changes impact, two of the owners (Erik & Dmitry) are directly involved with ‘instantiation reform’ proposal on TC39. Therefore we believe now is the right time to proceed with ES6 classes’ implementation.
# Interest from other vendors
None of browser vendors currently ship ES6 classes, even though both Firefox and IE stated the intent of doing so.
# Technical considerations
Design document:
https://docs.google.com/a/chromium.org/document/d/1UaIt5SeiM-DI8tSOhtM39eSOpjkDiv2UxP9eFK35Rno/
Cheers,
这些被GO抛弃的东西怎么又跑到JS上来了，就是不知道对性能没有影响。 不过Java程序员用起来应该很顺手。