npm-install-to

Provides an API for npm install through globally installed npm.
See also: runtime-npm-install

introduction

key features

• does not introduce npm as dependency, by using globally installed npm
• allows installing modules to a specific directory
• optimized for performance: calling with already installed packages should be

as quick as possible

caching

Does not attempt to install modules that are found in <installPath>/node_modules with satisfying install parameters in package.json.
For example, if one of the packages to be installed is ramda@0.26.0. the library will check if package.json at <installPath>/node_modules/ramda contains { _requested: { type: "version", fetchSpec: "0.26.0" } }. Failing that, it will install ramda at the given version.
The same strategy is applied for tags as well.

global npm

As mentioned, this module uses globally installed npm, through a module called global-npm, instead of introducing npm as its own dependency. This may present a problem, in case the global npm is incompatible with the way this library uses npm's programmatic API.
The library runs the actual npm.commands.install() in a child process. The only reason for that is that programmatic npm install pollutes stdout of the process. Spawning a child process seemed like a better idea than monkey patching console.log for the duration of the npm install part.

install

npm install npm-install-to

API

The module exports following functions:

npmInstallTo(installPath: string, packages: string[], options: Object): Promise<Object>

installPath: string

A path in the local filesystem where modules should be installed to. It does not have to exist.

packages: string[]

A list of packages as strings, corresponding to how npm install command is given packages to be installed. More information on that available with `npm help install`.

options: Object

{
  // Exclude packages from being installed, but return them if already installed
  skipInstall: string[],
  // Force specific packages to be installed regardless of if they exist already
  forceInstall: string[],
}

Use skipInstall option to exclude specific packages from being installed. They will still be in the return value, but the function won't check if they have to be installed.
The option forceInstall can be used to schedule some packages to be installed regardless of if they are already installed with the same version.
Returned promise resolves to an object containing output from npm install, and locations of installed modules.
For example, given the input:

const { npmInstallTo } = require('npm-install-to')
npmInstallTo('/path/to/dir', [
  'treis@2.6.0',
  'ramda@latest',
  'lodash'
])

The resolved object might look as follows:

{ npmOutput:
   '+ ramda@0.26.1\n+ treis@2.6.0\n+ lodash@4.17.11\nadded 1 package from 2 contributors, updated 2 packages and audited 713 packages in 1.854s\nfound 0 vulnerabilities',
  packages:
  { 'treis@2.6.0': '/path/to/dir/node_modules/treis',
    'ramda@latest': '/path/to/dir/node_modules/ramda',
    lodash: '/path/to/dir/node_modules/lodash' } }

getPkgsToBeInstalled(installPath: string, packages: string[]): Promise<string[]>

Use to check which given packages would be installed, if npmInstallTo were to be run with them.

example

const { npmInstallTo } = require('npm-install-to')

npmInstallTo(`${process.env.HOME}/test-dir`, [
  'treis@2.6.0',
  'ramda@latest',
  'lodash'
])
  .then(console.log)
  .catch(console.log)

debugging

Uses debug for debugging messages.
Enabling them with export DEBUG=npm-install-to might provide helpful information.

related projects

• npmi