This is a python implementation of the official npm/validate-npm-package-name package for validating npm package names.

$ pip install npm_package_validator

$ npm_package_validator my-package

Validate an npm package name like this:

import npm_package_validator
# Fails! Uppercase is not allowed for new packages
assert npm_package_validator.valid_new_package('MY-package')

However, upper case names used to be allowed and so validating as an old, existing package succeeds:

assert npm_package_validator.valid_old_package('MY-package')  # Succeeds!

When using the CLI, you can use the --old flag.

If you want to know whats wrong with a name, use:

from npm_package_validator.validate import validate_package
errors, warnings = validate_package('MY-package')
print("Errors: %s" % ", ".join(errors))
print("Warnings: %s" % ", ".join(warnings))

A valid new package name must have neither errors nor warnings. Existing packages can have warnings, as the npm validation rules have become stricter over time.

The official javascript implementation npm/validate-npm-package-name.

All of this happens when you run invoke pre-commit.