Getting Started with Node.js

This tutorial will teach you how to build a “Hello, World!” chute using Node.js and Express.


Make sure you have Node.js (v6 or newer) installed as well as ParaDrop pdtools (v0.9.2 or newer).

pip install pdtools>=0.9.2

Set up

Make a new directory.

mkdir node-hello-world
cd node-hello-world

Create a chute configuration

Use the pdtools interactive init command to create a paradrop.yaml file for your chute.

python -m pdtools chute init

Use the following values as suggested responses to the prompts. If you have a different version of pdtools installed, the prompts may be slightly different.

name: node-hello-world
description: Hello World chute for ParaDrop using Node.js.
type: light
image: node
command: node index.js

The end result should be a paradrop.yaml file similar to the following.

command: node index.js
config: {}
description: Hello World chute for ParaDrop using Node.js.
name: node-hello-world
type: light
use: node
version: 1

The pdtools chute init command will also create a package.json file for you if one did not already exist, so there is no need to run npm init after running pdtools chute init.

Install Dependencies

Use the following command to install some dependencies. We will be using Express as a simple web server.

The --save option instructs npm to save the packages to the package.json file. When installing the chute, ParaDrop will read package.json to install the same versions of the packages that you used for development.:

npm install --save express@^4.16.1

Develop the Application

We indicated that index.js is the entrypoint for the application, so we will create a file named index.js and put our code there.

const express = require('express')
const app = express()

app.get('/', function (req, res) {
  res.send('Hello, World!')

app.listen(3000, function() {
  console.log('Listening on port 3000.')

Run the application locally with the following command.

node index.js

Then load http://localhost:3000/ in a web browser to see the result.

Wrap Up

The web server in this application listens on port 3000. We need to include that information in the paradrop.yaml file as well. Use the following command to alter the configuration file.

python -m pdtools chute set config.web.port 3000