Logging can be used to understand the behavior of a web application and detect potential problems. It should be considered as important as unit testing when creating an application. It's not only useful for tracking down bugs but also for other reasons:
Performing business analysis
Used in conjunction with other tools to trigger alerts
Creating various statistics
Performance analysis
There are lots of logging modules in NPM that we can use. However, in this chapter, we will focus on bunyan (https://www.npmjs.org/package/bunyan). This module has been battle-tested in production at Joyent and has a lot of useful features, as follows:
Logs are structured using the JSON format
It has the ability to specify custom destinations for logs (such as custom streams, files, and logfile rotation)
It provides support for the custom serialization of objects (it comes bundled with serializers for the request, response, and error objects)
It comes with a great CLI tool that...