On May 13, 2013, at 1:50 PM, Erik Arvidsson wrote: > The way that WebIDL require Object.prototype.toString to return "[object > TypePrototype]" for the interface prototype object and "[object Type]" for > the instances seems to imply that every instance needs to have an own > @@toStringTag. > > http://people.mozilla.org/~jorendorff/es6-draft.html#sec-15.2.4.2 > http://dev.w3.org/2006/webapi/WebIDL/#es-environment > > If an instance does not have its own @@toStringTag, Object.prototype.toString > will read through to the [[Prototype]] which would return the wrong string.
Well, toString just does a [[Get]] for @@toStringTag. You are perfectly free to implement it as a get accessor that takes into account whether the this value is an instance or a prototype object. Not sure whether the complexity is really worth it in most cases. I considered building something like that into Object.prototype.toString but it seemed hard to justify and there was no (ES) legacy reason for doing so. The preferred way to over-ride toString should be via a toString method, not via @@toStringTag. Allen
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