Debugging and monitoring

I recently struggled with monitoring FE application.
I had no idea how to monitor errors in your SPA, so I made some research of cloud monitoring tools, but I was not able to decide which one to choose.
You are also able to listen window events, but is it good enough?
Every tool has pros and cons.
Could you help me with your experience and how do you monitor you application?
I will appretiate your comments.

I have just one more thing to ask, if you debug node.js application do you use just console.log to understand what is going on, or do you use debugger?