[proposal] Persistent variables in functions/methods

[Jacob Pratt]

Can you explain the difference between this and static properties? At quick
glance, I don't see any.

Would this not work?

```javascript
function foo(n) {
    this.counter++;
    return n * a;
}
foo.counter = 0;
foo.httpRE = /^https?/;
```


jhpratt

On Tue, Jul 17, 2018 at 12:56 AM, Neek Sandhu <neek.sandhu at outlook.com>
wrote:

> It'd be really useful to have variables inside methods/functions that are
> initialized once, reused for subsequent calls and live as long as
> containing scope i.e the function itself.
>
> > not to be confused with `static` properties
>
> ## Use Cases
>
> Almost every app has a function or method that needs to "preserve" some
> state across multiple calls, a counter for example. Current ways out of
> this situation are either closures created with IIFE's or making those
> variables top-level. Both of which are ugly. I think the same could be done
> much more neatly with persistent variables.
>
> ## Example
>
> ```javascript
> function foo(n) {
>     // initialized on first call to foo, persists for subsequent calls
>     persist let counter =  0;
>
>     // this way JS engine won't have to recompile the pattern everytime
>     persist const httpRE = /^https?/;
>
>     counter++;
>     return n * a;
> }
> ```
>
> is 1:1 as
>
> ```javascript
> let foo = (() => {
>     let counter = 0;
>     const httpRE = /^https?/;
>     return (n) => {
>         counter++;
>         return  n * a;
>     }
> })()
> ```
>
>
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