The bytes used for code can be reduced. Used redundancy in the original
code to handle both cases at the actual examples at OP.
```JSON.stringify()``` and ```replace()``` could be used. The original
proposal mentions ```JSON```, though includes the case of

```
const { y =? 'a' } = { y: undefined }; // z === 'a'
```
which is not valid ```JSON``` but a JavaScript plain object. The brief
example handles ```JSON``` and/or JavaScript plain object input.

There would probably at least that amount of code to implement the
extension to the ```=``` operator in JavaScript.

On Fri, May 10, 2019 at 8:58 AM Oliver Dunk <oliver at oliverdunk.com> wrote:

> > Given input valid JSON JSON.parse() or JSON.stringify() replacer
> function can be utilized to substitute "undefined" for null.
>
> guest271314, that’s a lot of code! It feels like if anything, your example
> backs up the proposal.
>
> > `const { z =? 'a' } = { z: null };`
>
> I’m not sure I like the proposed syntax. The question mark indicates to me
> that it’s the value on the lhs that’s optional - when in reality, it’s the
> other way around.
> _______________________________________________
> es-discuss mailing list
> es-discuss at mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
>
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The bytes used for code can be reduced. ```JSON.stringify()``` or ```JSON.parse()``` and ```replace()``` could be used. The original proposal mentions ```JSON```, though includes the case of

```
const { y =? 'a' } = { y: undefined }; // z === 'a'
```
which is not valid ```JSON``` but a JavaScript plain object. The brief
example handles ```JSON``` and/or JavaScript plain object input. 

Is the actual input a ```JSON``` string? 

There would probably at least that amount of code to implement the
extension to the ```=``` operator in JavaScript.