Interesting, can you give a link? I tried to find it, it&#x27;s not here <a href="https:&#x2F;&#x2F;github.com&#x2F;tc39&#x2F;ecma262" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;tc39&#x2F;ecma262</a> Only mention is &quot;Typed objects&quot; but that is not TS-like annotation.