Hey there,
You're looking for someone to fix your Cocos2d-x game and also the back-end. You've found the right person.
I have a decade worth of experience in Programming, and several years in Javascript alone. I've used plenty of NodeJS and consider myself an expert. I'm not sure which language you're using for the Cocos2d-x, but from the looks of it, I have experience in all of them (C++, Lua, Javascript).
I'm hard-working and confident in my abilities. If you pick me, you will be guaranteed a swift delivery of a quality product.
Looking forward to working with you.