How to use the command 'npm query' (with examples)

The npm query command is used to print an array of dependency objects using CSS-like selectors. It allows users to filter and display specific dependencies based on various criteria.

Use case 1: Print direct dependencies

Code:

npm query ':root > *'

Motivation: This use case is useful when you want to get a list of all the direct dependencies of your project.

Explanation:

• npm query is the command itself.
• :root > * is the selector expression used to filter the dependencies. It selects all direct dependencies.

Example output:

[
  {
    "name": "dependency1",
    "version": "1.0.0"
  },
  {
    "name": "dependency2",
    "version": "2.3.1"
  },
  ...
]

Use case 2: Print all direct production/development dependencies

Code:

npm query ':root > .prod|dev'

Motivation: This use case is helpful when you want to differentiate between production and development dependencies and view them separately.

Explanation:

• npm query is the command.
• :root > .prod|dev is the selector expression that selects all direct dependencies that have the class .prod or .dev.

Example output:

[
  {
    "name": "dependency1",
    "version": "1.0.0"
  },
  {
    "name": "dependency2",
    "version": "2.3.1"
  },
  ...
]

Use case 3: Print dependencies with a specific name

Code:

npm query '#package'

Motivation: This use case is useful when you want to search for a specific dependency by its name.

Explanation:

• npm query is the command.
• #package is the selector expression that selects all the dependencies with the name “package”.

Example output:

[
  {
    "name": "package",
    "version": "1.0.0"
  }
]

Use case 4: Print dependencies with a specific name and within a semantic versioning range

Code:

npm query #package@semantic_version

Motivation: This use case allows you to find specific versions of a dependency within a semantic versioning range.

Explanation:

• npm query is the command.
• #package@semantic_version is the selector expression that selects the dependency named “package” with a version within the specified semantic versioning range.

Example output:

[
  {
    "name": "package",
    "version": "1.2.0"
  }
]

Use case 5: Print dependencies which have no dependencies

Code:

npm query ':empty'

Motivation: This use case helps you find dependencies that do not have any dependencies of their own. These dependencies are usually considered “leaf” dependencies.

Explanation:

• npm query is the command.
• :empty is the selector expression that selects all the dependencies with no dependencies.

Example output:

[
  {
    "name": "dependency1",
    "version": "1.0.0"
  },
  {
    "name": "dependency2",
    "version": "2.3.1"
  },
  ...
]

Use case 6: Find all dependencies with postinstall scripts and uninstall them

Code:

npm query ":attr(scripts, [postinstall])" | jq 'map(.name) | join("\n")' -r | xargs -I {} npm uninstall {}

Motivation: This use case is helpful when you want to uninstall all dependencies that have post-install scripts.

Explanation:

• npm query ":attr(scripts, [postinstall])" selects all dependencies that have a postinstall script.
• jq 'map(.name) | join("\n")' -r extracts only the names of the dependencies from the output.
• xargs -I {} npm uninstall {} uninstalls each dependency returned by the previous command.

Example output:

Uninstalling dependency1...
Uninstalling dependency2...
...

Use case 7: Find all Git dependencies and print which application requires them

Code:

npm query ":type(git)" | jq 'map(.name)' | xargs -I {} npm why {}

Motivation: This use case is useful when you want to find all Git dependencies in your project and determine which application requires them.

Explanation:

• npm query ":type(git)" selects all Git dependencies.
• jq 'map(.name)' retrieves only the names of the dependencies from the output.
• xargs -I {} npm why {} checks which application requires each Git dependency.

Example output:

Dependency1 is required by application1
Dependency2 is required by application2
...

Conclusion:

The npm query command provides a powerful way to filter and display specific dependencies based on various criteria. It allows users to easily manage and understand their project’s dependencies.