Conditional object properties

kdex kdex at kdex.de
Wed Nov 2 13:04:36 UTC 2016


I'd imagine that from an engine point of view, this means that fewer
object shapes land in memory, at least for v8.

Reducing the number of object shapes currently boils down to using an
object literal and setting the properties to `value || null` instead of
extending the object with new properties imperatively.

On Wednesday, November 2, 2016 12:38:05 PM CET Isiah Meadows wrote:
> What benefit would this bring over imperatively adding properties?
> 
> On Wed, Nov 2, 2016, 08:18 Luke Mitchell <luke at enki.com> wrote:
> 
> > Hi all,
> >
> > I often come across a situation where I wish to extend an object
> > (usually an argument for an API request) if a particular condition is
> > satisfied, such as the presence of a function parameter. Currently the
> > only way to do this is by assigning the object to a variable, checking
> > the condition using an `if` statement and then extending the object. I
> > am proposing the inclusion of an operator that allows a property to be
> > included, subject to a particular condition, inside the object
> > definition.
> >
> > The operator looks like this:
> >
> > ```
> > let obj = {
> >   cond ? prop: value
> > };
> >
> > ```
> >
> > The operator could also be used with a block statement, allowing
> > multiple properties to be included:
> >
> > ```
> > let obj = {
> >   cond ? {
> >     prop1: value1,
> >     prop2: value2
> >   }
> > };
> > ```
> >
> > I have created a draft proposal and would love to hear any thoughts
> > you have on the matter. You can find it on my GitHub, at the link
> > below.
> >
> > https://github.com/lukem512/proposal-condition-property-definitions
> >
> > Kind regards,
> > Luke
> > _______________________________________________
> > es-discuss mailing list
> > es-discuss at mozilla.org
> > https://mail.mozilla.org/listinfo/es-discuss
> >
> 



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