[whatwg] Serialization of expandos on String / Boolean / Number objects

Dumez, Christophe christophe.dumez at intel.com
Thu Aug 23 12:13:28 PDT 2012


The latest specification of the structured clone algorithm [1] does
not indicate that we are supposed to serialize expandos on objects
such as String, Boolean or Number.

For example:
var str = new String("test");
str.foo = 3;
window.postMessage(str, "*");

Isn't str.foo property supposed to be serialized? If I read the
specification correctly, it is not:
If input is a String object

         Let output be a newly constructed String object with the same
value as input.

Is this behavior really intended? I think it would make sense to
serialize the properties attached to such objects.

[1] http://www.whatwg.org/specs/web-apps/current-work/#safe-passing-of-structured-data

Christophe Dumez
Linux Software Engineer, PhD
Intel Finland Oy - Open Source Technology Center

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