LMSinitialize() and before unloading the CC file would pass LMSfinish() to the SCORMAPI.js file 
there are numerous other values like lesson_Status etc. which are done by LMSsetValue() or LMSGetValue() to set scores, status or retrieve bookmarks etc. 
you would use data pairs LMSSetValue ("lesson_status", "Completed") The LMSfinish() is usually set with a BeforeUnload action 

So, how would I best use you great new behavior DoOnFunctionCall and does every possible value pair of SCORM that I want to use be assigned as vars under "FunctionCall" e.g., Var Init=LMSinitialize(); Var Quit=LMSFinish();

const radsToDegrees = 180 / Math.PI;
function quaternionToEuler(q) {
    var w = -q.w;
    var x = q.x;
    var y = q.y;
    var z = -q.z;

    var t = 2 * (w * y - z * x);

    return {
        // X-axis rotation
        x: (Math.atan2(2 * (w * x + y * z), 1 - 2 * (x * x + y * y))) * radsToDegrees,
        // Y-axis rotation
        y: (t >= 1 ? Math.PI / 2 : (t <= -1 ? -Math.PI / 2 : Math.asin(t))) * radsToDegrees,
        // Z-axis rotation
        z: (Math.atan2(2 * (w * z + x * y), 1 - 2 * (y * y + z * z))) * radsToDegrees,
    };
}