[k__]

I had the impression, the ECMAScript spec would only accept proposals "after" they were implemented by the major players.

How did PTC sneak into the spec?

[cwmma]

It predates the current model individual proposals that are worked on separately.

[kall]

Aside from the points below, it's implemented in Safari IIRC?

[hajile]

It was also implemented in v8

[Kwantuum]

from the linked PTC proposal in the article (https://github.com/tc39/proposal-ptc-syntax):

> Unfortunately, the TC39 process at this time did not require heavy implementation involvement and so while many implementers were skeptical, the feature was included and standardized as part of ES6.