Ternary operator enhancement proposal

Claude Pache claude.pache at gmail.com
Wed Nov 13 14:48:09 UTC 2019



> Le 13 nov. 2019 à 03:43, devlato <ecma6 at devlato.com> a écrit :
> 
> Hey folks,
> 
> not sure if you haven't discussed something similar, but what do you think about making an enhancement for the ternary operator, to make it more powerful? 
> I've created a small explanatory doc on GitHub: https://github.com/devlato/proposal-ternary-placeholder
> 
> Warmest regards,
> Denis
> 

The generic problem is: you do some computation, and you want to reuse the result of that computation later.

The generic solution is to use a temporary variable:

```js
// declare a temporary variable at the top of some scope
var _;

// later, use it:
const X = () => (_ = x?.y?.z) ? doSomethingWithValue(_) : null;
```

Now, you are not satisfied with the existing solution, and you want to avoid declaration of temporary variables in some outer scope...? Maybe:

```js
const X = () => (#1 = x?.y?.z) ? doSomethingWithValue(#1) : null;
```

(Any similarity with https://developer.mozilla.org/en-US/docs/Archive/Web/Sharp_variables_in_JavaScript <https://developer.mozilla.org/en-US/docs/Archive/Web/Sharp_variables_in_JavaScript> is not at all fortuitous.) However, I’m not convinced that the need to declare your temporary variables is such a problem that it is worth the introduction of new syntax.


—Claude
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