On: Decaffeinating a Large CoffeeScript Codebase Witho...

[smilekzs]

Plain vanilla JS (and therefore TypeScript) still lacks one killer feature from the Coffee family: Null propagation operators (`a ? b` => `a != null ? a : b`, `a?.x` => `a == null ? null : a.x`, etc). Even C# has it.

[sudowork → smilekzs]

I agree, it's one of the features we'll miss.

There is a Stage 1 Null Propagation proposal: https://github.com/tc39/proposal-optional-chaining

[evan_ → sudowork]

There's a babel transform for this in case you want to start using it now, before browsers support it:

https://github.com/babel/babel/tree/7.0/packages/babel-plugi...

[smilekzs → evan_]

I want to use TypeScript too, which will probably not adopt it until standardization.

[DanRosenwasser → smilekzs]

We definitely want to implement it! But many parts of that specification are still in flux, so like you said, we'd like to see the proposal stabilize first to avoid problems.

[sudowork → evan_]

Thanks for the tip! Given some of the lessons we've learned with CoffeeScript, we'll most likely wait until proposals hit at minimum stage 3 before adopting them.

[btown → evan_]

I've been waiting for this for years. Even considered forking Babel... it's been a long time coming :)

[abritinthebay → smilekzs]

Given null is generally non-idiomatic in JS (it's there, but most best practices say to avoid it) I think that's likely by design.

However the `a?.b` form is coming (it's not just null propagation, it's an Existence Operator). It's called "optional chaining"

https://github.com/tc39/proposal-optional-chaining

[smilekzs → abritinthebay]

> I think that's likely by desig

Fine.

s/null/undefined

The problem still exists.

[abritinthebay → smilekzs]

I think calling it a problem is a bit melodramatic.

A cleaner syntax is nice for sure, but it’s not exactly unworkable as is (and promotes flatter data, generally a good thing).

But yes, it’ll be nice if/when the new syntax drops.

[alanh → smilekzs]

The other killer feature that is still missing is multi-line regex with inline comments. I know, you shouldn't be writing big regexes if possible… but when you need to, it's so nice to be able to actually explain what the heck you are doing!

[Jakob → smilekzs]

The first one kind of works with `a || b`. Returns b if a is falsey (null, undefined, 0, "").

[smilekzs → Jakob]

> kind of works

!== works