Few issues:
1. This is already technically valid code: `cond?!fn:orElse` is equivalent
to `cond ? !fn : orElse`
2. Have you considered `do` expressions (stage 1 proposal)? They work a lot
like IIFEs, but allow easy definition of computed constants.
3. Have you considered using in-condition assignment or just factoring out
the computed condition into a separate variable? Sometimes, a little
verbosity helps.
Using `do` expressions, your second code sample would look like this:
```js
const newFoo = do {
let x = getSomething();
if (x) {
doSomethingFirst();
x.doSomething();
} else {
doSomethingElse();
}
};
```
On Tue, Sep 19, 2017, 08:33 Michael Rosefield <[email protected]>
wrote:
> (I've also put this on reddit
> <https://www.reddit.com/r/javascript/comments/7129tn/proposal_resultforwarding_ternary_operator/>,
> which I've copied this from. Hope the formatting doesn't go haywire...)
>
> First course of action for this proposal is, obviously, to
> come up with a better name for it....
>
>
> Motivation
>
> As with the 'optional chaining' proposal for tc39
> <https://github.com/tc39/proposal-optional-chaining>, this operator is a
> way to avoid excess and annoying code from safety-checking.
>
> The optional chaining proposal, above, follows a chain and short-circuits
> it upon acting on a null object, returning a safe '*undefined*' result;
> it can be thought of as an extended '*if*' sequence. It looks like this:
>
> // safeVal = result of someProp, or undefined if looking for props on null obj
> const safeVal = blah?.someMethod()?.someProp;
>
> This proposal provides for an '*else'* scenario, particularly in
> situations where chaining isn't appropriate, by forwarding the result of a
> truthy conditional check to a single-parameter function.
>
>
> Syntax
>
> *condition ?! fn : expr*
>
> Parameters
>
> - condition: any condition, *identical to use in standard ternary*
> - fn: function taking single parameter, which is the result of
> evaluating *condition*
> - expr: any expression, *identical to use in standard ternary*
>
>
> Usage Example
>
> // temporary variable
> const temp = getSomething(),
> foo = temp ? doSomething(temp) : doSomethingElse();
>
> // repeated code, possible side-effects
> const foo2 = getSomething() ? doSomething(getSomething()) : doSomethingElse();
>
> // proposal, no chaining
> const newFoo = getSomething() ?! x => doSomething(x) : doSomethingElse();
>
> // proposal, chaining
> const newFoo = getSomething() ?!
> x => {
> doSomethingFirst();
> return x.doSomething();
> } :
> doSomethingElse();
>
>
> Notes
>
> -
>
> The choice of '?!' is entirely arbitrary and not a core part of the
> proposal.
> -
>
> The result of the conditional check is not passed on to the falsey
> path, because it seems pointless to do so.
>
> _______________________________________________
> es-discuss mailing list
> [email protected]
> https://mail.mozilla.org/listinfo/es-discuss
>
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
