quick recap:
why is this not possible, giving the ability to understand through typeof
if there is a value or not?
```javascript
// defined as const
// reserved in this scope
// but not assigned yet
const WHATEVER;
if (condition) {
// first come, first serves
WHATEVER = 123;
// that's it! const defined for the whole scope
// immutable from now on
} else {
WHATEVER = 456;
}
console.log(WHATEVER);
// should throw as it is now
var WHATEVER;
let WHATEVER;
function WHATEVER(){}
```
It seems to me this might be a desired behavior. Any chance this will
happen? NO is a valid answer, thanks.
On Thu, Dec 19, 2013 at 4:31 PM, Andrea Giammarchi <
[email protected]> wrote:
> it's not invalind, it's what I am talking about.
>
> There is no way to conditionally define constants if not through an inline
> ternary or a returned value from a closure otherwise, by design, a second
> variable (garbage, pointless hoisting pollution) is mandatory.
>
> The only way to avoid this is to evaluate ... it looks dirty, it works "as
> I would like to" ... as any other C like language I know would do with
> constants without the old var hoisting problem.
>
> ```javascript
> try {
> new Proxy({},{});
> eval('const ES6_PROXY=true');
> } catch(nope) {
> eval('const ES6_PROXY=false');
> }
>
> console.log(ES6_PROXY);
> ```
>
> Does this make sense?
>
>
>
> On Thu, Dec 19, 2013 at 3:50 PM, Rick Waldron <[email protected]>wrote:
>
>>
>>
>>
>> On Thu, Dec 19, 2013 at 6:18 PM, Andrea Giammarchi <
>> [email protected]> wrote:
>>
>>> Rick thanks but I wasn't strictly asking for solutions because I have
>>> one, I was rather pointing at the fact that there is no solution and by
>>> design we need to create garbage.
>>>
>>> Your last example talks itself ... why do we need to define another
>>> variable in that scope? That is annoying, imho ... I don't want define a
>>> `tmp` like variable per each const type I'd like to address down the road,
>>> you know what I mean?
>>>
>>> I cannot even drop that var, so that's a potential leak in the global
>>> scope/context if not loeaded through modules while I might want to define
>>> that constant globally (and maybe name-spaced, but that's not the issue
>>> here)
>>>
>>> IE11 ... I don't have it with me now, would this work nicely ? I think
>>> no :-(
>>>
>>> ```javascript
>>> let ES6_PROXY = true;
>>> try {
>>> new Proxy({},{});
>>> } catch(o_O) {
>>> ES6_PROXY = false;
>>> }
>>> const ES6_PROXY = ES6_PROXY;
>>> ```
>>>
>>
>> It doesn't matter if I ran this in IE11 today or Firefox/Chrome/whatever
>> when those implementations are updated: let and const bindings don't allow
>> _redeclaration_ of bindings that already exist in that scope.
>>
>>
>>
>>>
>>> So const are not as simple and straight forward to be defined as it is
>>> in C or others and because these have been defined on top of `var` hoisting
>>> behavior.
>>>
>>> ```C
>>>
>>> #ifdef WHATEVER
>>> static int const NAME = 1;#else
>>> static int const NAME = 0;
>>>
>>>
>>>
>>> #endif
>>>
>>> ```
>>>
>>> Thoughts?
>>>
>>
>> It's an invalid comparison, unless you're saying you want ifdefs in JS.
>> This is an apples-to-apples comparison:
>>
>> C:
>>
>> if (1) {
>> static int const A_VAL = 1;
>> }
>> printf("%d", A_VAL);
>>
>> // error: use of undeclared identifier 'A_VAL'
>>
>> JS:
>>
>> if (1) {
>> const A_VAL = 1;
>> }
>> console.log(A_VAL);
>>
>> // 'A_VAL' is undefined
>>
>>
>> Rick
>>
>>
>
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