This is not a user experience question. Questions should be related to user experience problems that you have a question about. Requesting information on a logo isn't such a question and isn't suited to a StackExchange site.
actually this is a user experience question, most notably because user experience is subjective.
In response to your second question: I guess if I must choose then I would go for any icon in my existing house style with these two features:
- Capitals "JS"
- Indication that the icon's about code
To add to this, see there's this related icon:
- JScript: Microsoft's implementation of ECMAScript