gistfile1.txt

var request = require('request');

var host = 'localhost:8080';    
var username = 'tenant@thingsboard.org';   
var password = 'tenant';         

var user = {
    'username': username,
    'password': password
};

var options = {
    method: 'post',
    url: 'http://' + host + '/api/auth/login',      
    headers: {
        'Content-Type': 'application/json',
        'Accept': 'application/json',
    },
    body: JSON.stringify(user),
};

request(options, function(error, response, body) {
    console.log('error:', error);
    console.log('statusCode:', response && response.statusCode);
    console.log('body:', body);
});

Go to directory of your project

mkdir TestProject
cd TestProject

Make this directory a root of your project (this will create a default package.json file)

npm init --yes

Install required npm module and save it as a project dependency (it will appear in package.json)

npm install request --save

Create a test.js file in project directory with code from package example

var request = require('request');
request('http://www.google.com', function (error, response, body) {
  if (!error && response.statusCode == 200) {
    console.log(body); // Print the google web page.
  }
});

Your project directory should look like this

TestProject/
- node_modules/
- package.json
- test.js

Now just run node inside your project directory

node test.js