Questions about writing/debugging the javascript code should go on stack overflow, but questions about game functionality and strategy should fit in here on Arqade.
In fact, the screeps offical docs direct users to post their gameplay questions here:
If you have a question please do not hesitate asking on StackOverflow in case of coding issues and on Arqade in case of gameplay issues. Don't forget to add the tag 'screeps', we regularly monitor the questions and try to answer as soon as possible.