How to get the script return code

I am executing a sequence of (JavaScript) test scripts and need to trap the return code of each script as it finishes.

Is there a project or global variable that contains the current test status/return code?

For example, if a Log.Warning or Log.Error statement is executed, the script finishes with a warning/error return code. 

Is it possible to obtain this return code value and if so, how do you do it?