Based on a quick test I am not seeing this problem with a .js file.  It is part of a solution that also contains C++, VB and C# code.  Based on your description I have added this to a cpp file in my solution:
void Log(std::string strLogThis)
{
}
and this to my .js file:
function simpleListboxTest()
{
	var localTest;
	localTest;
	|
}
when I start typing "log" in C++ I see this:

So VA certainly knows about this function.  But when I type in the .js file I see this:

and I am not seeing any case correction effects, even though case correction is turned on.
Is your .js file part of a solution?  Do you even have a solution currently open?