Complex code is hard to read, test, and work on, even more so if we're trying to decipher somebody else's code. Fortunately, there's a tool to measure code complexity called complexity-report (https://www.npmjs.org/package/complexity-report).

As always, we need to install the module first so that we can use it:

$ npm i complexity-report ––save-dev

When running this tool, we must specify which folders it should ignore, so that we don't get reports for the dependencies used or code-coverage files:

$ ./node_modules/.bin/cr . --dirpattern '^((?!(test|node_modules|coverage)).)*$'

A sample output could look like the following screenshot:

We can also specify the desired format, which can be one of the following: plain, markdown, minimal, JSON, and XML.

Just like the code-coverage tool, this one also supports thresholds for things such as cyclomatic complexity or Halstead difficulty threshold. These represent software metrics that determine the complexity of a program...