v1.9.0 creates invalid json by including undefined values

[src-code]

There seems to be a regression in v1.9.0 where objects with undefined values are being included in the json output, which is invalid. For example:

serialize({
  "foobar": undefined
});

Output:

{"foobar":undefined}

This is not valid json, and will fail when run through JSON.parse()

In v1.8.0 this worked correctly with the following output:

{}

[src-code]

Closing this as I guess it's intentional that this lib creates a superset of json

[p-j]

Could you reopen as this looks like a breaking change that might have warranted a major version bump.

[okuryu]

I just released v1.9.1 (includes reverting #54) and v2.0.0 for this issue. Thanks!

• https://github.com/yahoo/serialize-javascript/releases/tag/v1.9.1
• https://github.com/yahoo/serialize-javascript/releases/tag/v2.0.0

[p-j]

Thanks for the quick fix @okuryu !