Fwd: Boolean equivalent to pre-increment and post-icnrement

[Steve Fink]

On 08/29/2018 12:13 PM, Bob Myers wrote:
> In the stupid idea of the day department, for some reason I have felt 
> the urge more than once in recent months for an operator which would 
> invert the value of a boolean variable while evaluating to its 
> pre-inversion value. For example:
>
> ```js
> if (bool!!) console.log("used to be true");
> ```
>
> The post-inversion case is less important since I can just write `if 
> (bool = !bool)`.

There's always

     if (counter++ & 1) console.log("used to be true");
     if (++counter & 1) console.log("is now true");

or (counter++ % 2) if you prefer. And you get a free cycle counter in 
the bargain! (At the cost of flatlining to false at 2**53.)

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