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Plain vanilla JS (and therefore TypeScript) still lacks one killer feature from the Coffee family: Null propagation operators (`a ? b` => `a != null ? a : b`, `

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 9y ago
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 https://github.com/tc39/proposal-optional-chaining
- evan_ 9y ago
  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-plugin-transform-optional-chaining https://github.com/babel/babel/tree/7.0/packages/babel-plugi...
  - sudowork 9y ago
    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 9y ago
    I've been waiting for this for years. Even considered forking Babel... it's been a long time coming :)
  - smilekzs 9y ago
    I want to use TypeScript too, which will probably not adopt it until standardization.
    - DanRosenwasser 9y ago
      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.
abritinthebay 9y ago
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 https://github.com/tc39/proposal-optional-chaining
- smilekzs 9y ago
  > I think that's likely by desig Fine. s/null/undefined The problem still exists.
  - abritinthebay 9y ago
    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.
Jakob 9y ago
The first one kind of works with `a || b`. Returns b if a is falsey (null, undefined, 0, "").
- smilekzs 9y ago
  > kind of works !== works
alanh 9y ago
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!

sudowork 9y ago

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

evan_ 9y ago
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-plugin-transform-optional-chaining https://github.com/babel/babel/tree/7.0/packages/babel-plugi...
- sudowork 9y ago
  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 9y ago
  I've been waiting for this for years. Even considered forking Babel... it's been a long time coming :)
- smilekzs 9y ago
  I want to use TypeScript too, which will probably not adopt it until standardization.
  - DanRosenwasser 9y ago
    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.

abritinthebay 9y ago

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

smilekzs 9y ago
> I think that's likely by desig Fine. s/null/undefined The problem still exists.
- abritinthebay 9y ago
  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.

Jakob 9y ago

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

smilekzs 9y ago
> kind of works !== works

alanh 9y ago

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!