ES accessor usage guidelines (Was: Map/Set.prototype.size)

Brendan Eich brendan at
Mon Oct 15 16:02:18 PDT 2012

Yehuda Katz wrote:
> On Mon, Oct 15, 2012 at 5:41 PM, Brendan Eich <brendan at 
> <mailto:brendan at>> wrote:
>     Yehuda Katz wrote:
>             * get/set accessor may have effects on 'set' (see the DOM) but
>             only on the receiver object (and unobservably, any
>         children that
>             become garbage, e.g. when trimming .length on an array-like).
>         DOM methods like `innerHTML=` seem to violate this particular
>         wording (but perhaps not the spirit?)
>     Definitely the spirit!
>     That's one of those "children become garbage" cases, unless I
>     misunderstand your point. "The receiver" for .innerHTML includes
>     all descendants.
> Yeah that makes sense, although the exact side-effects might be more 
> observable with DOM. Relatedly, are we specifically exempting 
> Object.observe and DOM Mutation observers from the "observability" 
> requirement?

Yes, or at least: I wasn't considering those (or Proxies, as David 
pointed out) in my "first cut".

Some of this must be excluded from any such "Design Rules".


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