I think Ash brings up a valid point here. From a usability point it is a clear win to use [], delete and in for WeakMaps and Maps.
On Sat, Aug 14, 2010 at 14:02, Mark S. Miller <[email protected]> wrote: > On Sat, Aug 14, 2010 at 1:01 PM, Ash Berlin <[email protected]> wrote: >> >> On 14 Aug 2010, at 07:22, Erik Arvidsson wrote: >> > I have a few questions regarding the WeakMap API. >> > >> > 1. Why isn't there a way to check for presence of a key (using >> > has/contains)? >> > >> > Given that undefined is a valid value it is not sufficient to just >> > return undefined for get >> >> Does the standard trick of: >> >> if (key in weakMapInstance) { } >> >> not work? > > It does not. A key is not a property name. A weak map is an object with two > own properties, names "get" and "set", whose values are the methods that > constitute the weak map API. > >> >> > >> > 2. Why isn't there a way to remove a key-value-pair? >> > >> > Setting the value to undefined is not the same. >> >> Again: >> >> delete weakMapInstance[key]; > > No. This syntax deletes named properties. > >> >> > 3. Why isn't there a way to iterate over the keys? >> > >> > I can see that this might be a security issue but iteration is useful >> > and security sensitive code can prevent iteration in several ways. >> >> Object.keys(weakMapInstance) > > No. Object.keys enumerates property names. > >> >> > >> > 4. Why does set throw if the key is not an object but get doesn't? >> > >> > Same would go for delete and has if those are added. >> >> >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss > > > > -- > Cheers, > --MarkM > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > > -- erik _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
