Object Extract Method Suggestion

[Bob Myers]

This has been discussed at length. You can search the archives for
"picking" or "pick notation" or "destructuring into objects". There are
several proposals. No one seemed too interested, although to me it's a
mystery why, since it would be one of the more useful language features I
can think of, with quite a low language design footprint. In one proposal
<https://github.com/rtm/js-pick-notation/blob/master/minimally-extended-dot-notation.md>,
what you want (without the defaults, although the proposal supports that
too) would be written

```
return obj.{a, c};
```

Bob

On Mon, May 8, 2017 at 4:47 PM, Matthew Robb <matthewwrobb at gmail.com> wrote:

> Personally I've been itching for object pattern-like pick syntax. I keep
> finding myself doing the following pattern:
>
> ```
> const {a=1,c=2} = obj;
> return {a,c};
> ```
>
> On May 8, 2017 6:37 AM, "Murat Gözel" <murat at gozel.com.tr> wrote:
>
>> Hey everyone,
>>
>> The idea came up while i'm filtering spesific view of web page's text
>> objects from whole context object. Objects are much more useful than any
>> other type in many cases. I find myself working with more javascript
>> objects project to project. Despite this, an object extract method can be
>> useful for many cases. You can think of it as the opposite of assign
>> method. It reduces the source object to a smaller object with only keys you
>> spesified.
>>
>> Looks like this:
>> ```javascript
>> Object.extract(SourceObject, ArrayOfKeys)
>> ```
>>
>> Example usage:
>> ```javascript
>> const contactPageExpressions = ['Follow Us', 'Phone', 'Email']
>>
>> const wholeContext = {
>>   'Welcome': {
>>     translation: 'Welcome'
>>   },
>>   'Follow Us': {
>>     translation: 'Follow Us'
>>   },
>>   'Phone': {
>>     translation: 'Phone Number'
>>   },
>>   'Email': {
>>     translation: 'Email Address'
>>   },
>>   'News': {
>>     translation: 'News'
>>   }
>> }
>>
>> const activeContext = Object.extract(wholeContext, contactPageExpressions)
>>
>> // Now we have an object that only has keys we want:
>> {
>>   'Follow Us': {
>>     translation: 'Follow Us'
>>   },
>>   'Phone': {
>>     translation: 'Phone Number'
>>   },
>>   'Email': {
>>     translation: 'Email Address'
>>   }
>> }
>> ```
>>
>> Since it works by matching keys, second parameter of the method can even
>> be a regular expression:
>>
>> ```javascript
>> // Get properties that has numbers.
>> Object.extract(source, /[0-9]/g)
>> ```
>>
>> Would like to hear your opinions.
>>
>> _______________________________________________
>> es-discuss mailing list
>> es-discuss at mozilla.org
>> https://mail.mozilla.org/listinfo/es-discuss
>>
>>
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