They resist expansion pretty strongly even if they love change.
Like, remember when Google wanted to put Dart in the browser natively? Nobody liked it, and now we're stuck with build steps for quite a while until JS finally adds typing, which might never happen, especially because insane people seem to think canvas+WASM is a good idea for anything but the most specialized uses...
The choice not to add Dart into Firefox and safari was made by the browser vendors. It had nothing to do with the JavaScript standards committee. But to your point I do think it would be great if typescript got first class support by V8 & friends. Type information could dramatically improve JavaScript execution speed. Meticulously deleting all the types before passing code to V8 seems like a very silly choice.
I’ve been working in rust the last few years. I wish rust were as open to change as JavaScript is! Generators (aka coroutines) have been sitting just out of reach in nightly the entire time I’ve used the language.
Like, remember when Google wanted to put Dart in the browser natively? Nobody liked it, and now we're stuck with build steps for quite a while until JS finally adds typing, which might never happen, especially because insane people seem to think canvas+WASM is a good idea for anything but the most specialized uses...