NPM's init command will scaffold out a valid json file for you project.

The commands for npm init are:-

mkdir myapis
cd myapis
npm init --yes

I have used --yes option with the above command, because I don't want to set author name, keywords, git urls etc. for the project. If you need to setup all these details you can use

npm init without --yes

The above command will create package.json file at the root level with content:

{
  "name": "myapis",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

 
The first thing you  do is, specify 'engines' key with your keyword in package.json:

User ( node -v ) bto check the version of node installed.

"engines": {
  "node": "6.2.2"
}

Use a .npmrc

By default, npm doesn't save installed dependencies to package.json. You need to do it manually like as follows:

npm install moment --save

--save flag is used to auto update package.json.

Even better, you can set these options in .npmrc file, as follows:-

 npm config set save=true

 npm config set save-exact=true

 cat ~/.npmrc

 Now, npm install moment, will automatically add moment to package.json.