Deviations between json2.js and the currently specified behaviour of JSON.stringify

Oliver Hunt oliver at apple.com
Thu Jun 4 20:48:19 PDT 2009


The definition of the JSON.stringify function (per 15.12.3) defines  
str and JO such that [[Get]] will be called twice for every serialised  
property on an object, which may have side effects if the property is  
a getter.

My testing shows that json2.js accesses each property only once, which  
makes more sense in my opinion as having side effects occur twice for  
each serialised getter seems odd in of itself, and has the potential  
to be more efficient.  Gecko currently matches the spec in this regard  
and calls getters twice.

Another issue is the arguments passed to the abstract operation str  
when serialising an array when a replacer function is provided.  The  
definition of the abstract operation JA says that str should be called  
with the arguments ToString(index) and value.  While technically this  
is necessary in order to perform the [[Get]] operation with key on  
host in the str, it has the effect of implying that when replacer is  
called the key given passed as an argument, the key should be of type  
String.  Currently no implementation (including json2.js) does this  
ToString conversion, so i think the specified algorithm needs to be  
corrected to remove the ToString from this point.

--Oliver

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