# npm-package-arg [](https://travis-ci.org/npm/npm-package-arg) Parses package name and specifier passed to commands like `npm install` or `npm cache add`, or as found in `package.json` dependency sections. ## EXAMPLES ```javascript var assert = require("assert") var npa = require("npm-package-arg") // Pass in the descriptor, and it'll return an object try { var parsed = npa("@bar/foo@1.2") } catch (ex) { … } ``` ## USING `var npa = require('npm-package-arg')` ### var result = npa(*arg*[, *where*]) * *arg* - a string that you might pass to `npm install`, like: `foo@1.2`, `@bar/foo@1.2`, `foo@user/foo`, `http://x.com/foo.tgz`, `git+https://github.com/user/foo`, `bitbucket:user/foo`, `foo.tar.gz`, `../foo/bar/` or `bar`. If the *arg* you provide doesn't have a specifier part, eg `foo` then the specifier will default to `latest`. * *where* - Optionally the path to resolve file paths relative to. Defaults to `process.cwd()` **Throws** if the package name is invalid, a dist-tag is invalid or a URL's protocol is not supported. ### var result = npa.resolve(*name*, *spec*[, *where*]) * *name* - The name of the module you want to install. For example: `foo` or `@bar/foo`. * *spec* - The specifier indicating where and how you can get this module. Something like: `1.2`, `^1.7.17`, `http://x.com/foo.tgz`, `git+https://github.com/user/foo`, `bitbucket:user/foo`, `file:foo.tar.gz` or `file:../foo/bar/`. If not included then the default is `latest`. * *where* - Optionally the path to resolve file paths relative to. Defaults to `process.cwd()` **Throws** if the package name is invalid, a dist-tag is invalid or a URL's protocol is not supported. ## RESULT OBJECT The objects that are returned by npm-package-arg contain the following keys: * `type` - One of the following strings: * `git` - A git repo * `tag` - A tagged version, like `"foo@latest"` * `version` - A specific version number, like `"foo@1.2.3"` * `range` - A version range, like `"foo@2.x"` * `file` - A local `.tar.gz`, `.tar` or `.tgz` file. * `directory` - A local directory. * `remote` - An http url (presumably to a tgz) * `registry` - If true this specifier refers to a resource hosted on a registry. This is true for `tag`, `version` and `range` types. * `name` - If known, the `name` field expected in the resulting pkg. * `scope` - If a name is something like `@org/module` then the `scope` field will be set to `@org`. If it doesn't have a scoped name, then scope is `null`. * `escapedName` - A version of `name` escaped to match the npm scoped packages specification. Mostly used when making requests against a registry. When `name` is `null`, `escapedName` will also be `null`. * `rawSpec` - The specifier part that was parsed out in calls to `npa(arg)`, or the value of `spec` in calls to `npa.resolve(name, spec). * `saveSpec` - The normalized specifier, for saving to package.json files. `null` for registry dependencies. * `fetchSpec` - The version of the specifier to be used to fetch this resource. `null` for shortcuts to hosted git dependencies as there isn't just one URL to try with them. * `gitRange` - If set, this is a semver specifier to match against git tags with * `gitCommittish` - If set, this is the specific committish to use with a git dependency. * `hosted` - If `from === 'hosted'` then this will be a `hosted-git-info` object. This property is not included when serializing the object as JSON. * `raw` - The original un-modified string that was provided. If called as `npa.resolve(name, spec)` then this will be `name + '@' + spec`.