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Properties of Error instances in the latest V8 included by node@0.6.6 are not enumerable. And thus cannot be serialized through JSON.stringify
> var err = new Error('wtf?');
> JSON.stringify(err)
'{"stack":"Error: wtf?\\n at [object Context]:1:11\\n at Interface.<anonymous> (repl.js:179:22)\\n at Interface.emit (events.js:64:17)\\n at Interface._onLine (readline.js:153:10)\\n at Interface._line (readline.js:408:8)\\n at Interface._ttyWrite (readline.js:585:14)\\n at ReadStream.<anonymous> (readline.js:73:12)\\n at ReadStream.emit (events.js:81:20)\\n at ReadStream._emitKey (tty_posix.js:307:10)\\n at ReadStream.onData (tty_posix.js:70:12)","message":"wtf?"}'
> Object.keys(err);
[ 'stack', 'arguments', 'type', 'message' ]
> Object.getOwnPropertyDescriptor(err, 'stack');
{ get: [Function], set: [Function], enumerable: true, configurable: true }
> process.versions.v8
$ node
> var err = new Error('wtf?');
> JSON.stringify(err);
> Object.keys(err);
[ ]
> Object.getOwnPropertyDescriptor(err, 'stack');
{ get: [Function], set: [Function], enumerable: false, configurable: true }
> console.dir('wtffff fuuuuuuu');
'wtffff fuuuuuuu'
> process.versions.v8

jfhbrook commented Jan 3, 2012

I can at least confirm that it works in v0.4.12 and not in v0.6.6. That's insane and annoying.


indexzero commented Jan 3, 2012

Same behavior when installing versions of Chrome using the target V8 versions.

I had the problem in v0.6.6. Was wondering why do we have a ghost error object!

Raynos commented Jan 3, 2012

Dirty hack fix would be something like having Error.prototype.toJSON return an object with the enumerable properties

Error.prototype.toJSON = function () {
  var json =  {};
  Object.getOwnPropertyNames(this).forEach(addToJSON, this);
  return json;

  function addToJSON(name) {
    var pd = Object.getOwnPropertyDescriptor(this, name);
    pd.enumerable = true;
    Object.defineProperty(json, name, pd);

I can confirm this is still an issue in v8 and node 0.10.15

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