node/deps/npm/lib/fetch-package-metadata.md

fetch-package-metadata

var fetchPackageMetadata = require("npm/lib/fetch-package-metadata")
fetchPackageMetadata(spec, contextdir, callback)

This will get package metadata (and if possible, ONLY package metadata) for a specifer as passed to npm install et al, eg npm@next or npm@^2.0.3

fetchPackageMetadata(spec, contextdir, tracker, callback)

• spec string | object -- The package specifier, can be anything npm can understand (see realize-package-specifier), or it can be the result from realize-package-specifier or npm-package-arg (for non-local deps).

• contextdir string -- The directory from which relative paths to local packages should be resolved.

• tracker object -- (optional) An are-we-there-yet tracker group as provided by npm.log.newGroup().

• callback function (er, package) -- Called when the package information has been loaded. package is the object for of the package.json matching the requested spec. In the case of named packages, it comes from the registry and thus may not exactly match what's found in the associated tarball.

In the case of tarballs and git repos, it will use the cache to download them in order to get the package metadata. For named packages, only the metadata is downloaded (eg http://registry.npmjs.org/package). For local directories, the package.json is read directly. For local tarballs, the tarball is streamed in memory and just the package.json is extracted from it. (Due to the nature of tars, having the package.json early in the file will result in it being loaded faster– the extractor short-circuits the uncompress/untar streams as best as it can.)