Exit Button Script

I've created course for my LMS with multiple branches and assessments unique to each branch. Each assessment has its own Results slide. To complete the course, users must pass their branch's assessement with a score of 80% or higher.

I'm using JavaScript (found on these forums) to send the score and completion status to the LMS. Works perfectly.

The issue I'm having is with the Exit Course trigger: If someone has compeleted the course and clicks Exit, the object's completion status and score are overwritten with a null value. I'm trying to solve this by changing what the Exit button does based on whether or not a user has achieved completion. If they have not, clicking Exit exits the course with the standard functionality. If they have completed, I'm using JavaScript to close the window (window.close(). The JavaScript works when I publish and run it locally but not when I run the course from the LMS.

My question to the forum: how can I close the course window in my LMS for completed users without overwriting the completion/score I've already sent using JavaScript?