Most recently I needed that to do polymorphic function dispatch on input argument type. More specifics can be found here: https://github.com/Gozala/method/blob/master/core.js#L121-127
This case may be quite exotic, but I remember running into this quite a lot, can't use cases unfortunately. BTW underscore has bunch of this utilities too: http://underscorejs.org/#objects that making me believe it's common enough case. Regards -- Irakli Gozalishvili Web: http://www.jeditoolkit.com/ On Monday, 2012-10-15 at 17:59 , Brendan Eich wrote: > Just curious: why did you need a nominal type test, rather than a "duck > type" test? > > /be > > Irakli Gozalishvili wrote: > > Hi, > > > > Today I had to deal with a value type detection in JS and that > > reminded me of all the pain associated with it, especially when > > dealing with values that may have come across the diff compartment / > > frame / context. `instanceof` is useless when dealing with objects > > from diff contexts, `typeof` is also pretty limited in a sense that it > > can detect weather value is array, error, map, set, etc.. not to > > mention it's awkwardnesses… > > > > Only solution that seems to work toady that is adopted by most popular > > JS libraries is: > > > > function type(value) { > > return Object.prototype.toString.call(value).split(' > > ')[1].split(']')[0].toLowerCase() > > } > > > > I don't actually know if that's supposed to work according to spec or > > if it's just an implementation coincidence that happen to > > work. Either way I would really welcome some standard > > solution preferably via function form (so that can be polyfilled today) > > to do type detection for all the built-ins and host objects. > > > > Aside main issue, it would be great if solution was compatible with > > mozilla's xpcom components too where one object my be > > queried with multiple interfaces and there for have multiple types. > > Also, above hack does not works with XPCOMs as > > Object.prototype.toString returns "[object > > XPCWrappedNative_NoHelper]", while actual toString returns something > > little more useful "[xpconnect wrapped (nsISupports, nsIURI, nsIURL)]" > > > > Regards > > -- > > Irakli Gozalishvili > > Web: http://www.jeditoolkit.com/ > > > > _______________________________________________ > > es-discuss mailing list > > [email protected] (mailto:[email protected]) > > https://mail.mozilla.org/listinfo/es-discuss > > > > >
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