Do you have any insight into how the TC39 process works, and how one might drive this work forwards? I feel like expression-orientation is the main thing missing from JavaScript at this point, and I'd love to contribute. But it's not at all clear to me how to actually do so.

https://github.com/tc39/proposal-do-expressions

Allows you to contain temporary variables to where they are needed, rather than having them remain active through the remainder of the current scope. You could do that with immediately invoked function expressions, but they are too verbose to be really viable for this. You could also use extra functions, but extra functions don't always make sense. Currently I'm frequently doing this:

Without do expression:

    let result;
    {
        let tmp = 123;

        result = tmp * 2;
    }

With do expression it would become this:

    let result = do {
        let tmp = 123;
     
        tmp * 2;
    }