Install Npm on Mac

First, install brew

#Install Home-brew
$ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

#uninstall Hone-brew
uby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/uninstall)"

Second, uninstall node and nvm which were installed by brew.

$brew uninstall --force node
$brew uninstall --force nvm

Next, install nvm

$touch ~/.bashrc
$curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash
$source ~/.bashrc
$command -v nvm 

If the above doesn't fix the problem, open your ~/.bash_profile and add the following line of code:
source ~/.bashrc
Refer to https://github.com/creationix/nvm#install-script

Last, install node

$nvm --version
# check installed nodes
$nvm ls
# for remote 
$nvm ls-remote --lts
# To download, compile, and install the latest release of node, do this:
$nvm install node
# for sepecific version name
$nvm install v8.9.4
$nvm use v8.9.4
#just use the installed version
$nvm use node
# set default node version
$nvm alias default v8.10.0

npm is installed with Node.js

Usage

All packages can be founded in https://www.npmjs.com/

Command

npm init

To make package.json

# -y default config 
$ npm init -y

npm install

All packages in package.json is supposed to install into node_modules

$ npm install
# Install lodash package[version name] and add it into dependencies
$ npm i [email protected]
# Install lodash and react
$ npm i lodash react
# The package will appear in  devDependencies
$ npm install node-tap --save-dev
# Install package globally,add it in ~/.nvm/versions/node/v8.10.0/lib/node_modules/create-react-app
$ npm install -g crate-react-app

npm ci

npm install can change package-lock.json because of npm version, different platform or somthing.
npm ci has node_modules intalled by only using package-lock.json. package-lock.json and package.json is different, throw an erors
Required npm 5.7.1

$ npm ci

npm ls

Show packlages installed

$ npm ls
# for global
$ npm ls -g

npm outdated

Show outdated package

$ npm outdated
# for global
$ npm outdated -g

npm update

Update all packages outdated

# according to package.json
$ npm update
$ npm install lodash@latest

npm uninstall package

Remove package form node_modues

$ npm uninstall lodash

Script

npm supports the "scripts" property of the package.json file,

{
  "name": "lookup-server",
  "version": "0.0.1",
  "private": true,
  "babel": {
    "presets": [
      "es2015",
      "stage-0"
    ]
  },
  "dependencies": {
    "babel-cli": "6.22.2",
    "babel-core": "6.22.1",
    "babel-preset-es2015": "6.22.0",
    "babel-preset-stage-0": "6.22.0",
  },
  "scripts": {
    "start": "npm run server",
    "server": "babel-node start-server.js"
  }
}

# pretest, test, posttest
$ npm test
prestop, stop, poststop
$ npm stop
prestart, start, poststart
$ npm start 
prerestart, restart, postrestart
$ npm restart
$ npm run server

Refer https://docs.npmjs.com/