Exploring npm-why (with examples)

1: Show why an npm package is installed

Code:

npm-why package

Motivation: Understanding why a specific npm package is installed can be crucial for managing dependencies and troubleshooting issues. By using the npm-why command with the desired package name, developers can gain insight into the reasons behind its installation.

Explanation: The npm-why command is followed by the package name for which you want to identify the installation reasons. It analyzes the dependency tree of the project and traces back the path that led to the installation of the specified package.

Example Output:

$ npm-why express

Path                                             Why
└─ project@1.0.0                                  │   package.json:8.0.0
   └─ express@4.17.1                              │   package.json:11.0.0
      ├─ accepts@1.3.7                            │   express@4.17.1
      ├─ array-flatten@1.1.1                      │   express@4.17.1
      ├─ body-parser@1.19.1                       │   express@4.17.1
      │  ├─ bytes@3.1.0                            │   body-parser@1.19.1
      │  ├─ content-type@1.0.4                     │   body-parser@1.19.1
      │  ├─ debug@2.6.9                            │   body-parser@1.19.1
      │  │  └─ ms@2.0.0                            │   debug@2.6.9
      │  ├─ http-errors@1.7.2                      │   body-parser@1.19.1
      │  │  ├─ inherits@2.0.4                       │   http-errors@1.7.2
      │  │  │  └─ util@0.10.3                        │   inherits@2.0.4
      │  │  ├─ setprototypeof@1.1.1                 │   http-errors@1.7.2
      │  │  ├─ statuses@1.5.0                       │   http-errors@1.7.2
      │  │  └─ toidentifier@1.0.0                   │   http-errors@1.7.2
      │  └─ qs@6.7.0                               │   body-parser@1.19.1
      ├─ content-disposition@0.5.3                 │   express@4.17.1
      ├─ content-type@1.0.4                        │   express@4.17.1
      ...

By running npm-why express, we obtain a tree-like structure that shows the dependency path through which the package “express” was installed. The “Path” column displays the modules that depend on “express”, while the “Why” column indicates the specific dependency or package version in the project’s package.json file that led to the installation. This information can help identify indirect dependencies that might be causing conflicts or unnecessary duplication.

This command is useful when investigating issues related to particular packages, especially if the installation was unexpected or if you want to understand the impact of updating a specific dependency.