node/deps/npm/doc/api/version.md

npm-version(3) -- Bump a package version

SYNOPSIS

npm.commands.version(newversion, callback)

DESCRIPTION

Run this in a package directory to bump the version and write the new data back to the package.json file.

If run in a git repo, it will also create a version commit and tag, and fail if the repo is not clean.

Like all other commands, this function takes a string array as its first parameter. The difference, however, is this function will fail if it does not have exactly one element. The only element should be a version number.