Update: I have made a very very simple JavaSript SCORM 2004 API (But still looking for some more mature code).
Update2: I have found a very nice project TinyLMS. It's SCORM 1.2 only, but I have negotiated with my client that SCORM 1.2 would be sufficient. So I am gonna make a solution based on TinyLMS.
Slowly growing it - https://github.com/cybercussion/SCOBot. This was focused more for the content implementation of SCORM 2004/1.2 Protocols. There is a Local_API_1484_11.js which is meant as a mimc of the LMS Runtime. This is light weight and not as robust as a full implementation, but a start at any rate. I based much the work on Claude Ostyn and countless other resources online (ADL, scorm.com etc ..)
If you are affiliated with a non-profit/non-commercial project get in contact with me. I have a more complete version of this.
I also have a bookmarklet for checking the status of content running on a LMS located at http://www.cybercussion.com/bookmarklets/SCORM.