JSD > Project: Build a Slackbot > Tutorial > Step 3: Set Up Node Application

Step 3: Set Up Node Application

Step 3: Set up Node Application

In this step we’re going to create a node application that will function as our server

1. Create project folder

Navigate to the appropriate lesson_0x_file in your class folder
Create a new folder named openweather-bot
Change directories into that folder

2. Run `npm init` to bootstrap the Node application

Run npm init from the command line (make sure you inside your newly created project folder)
Accept all of the default values (just press “enter” at every prompt)

3. Install the node packages (libraries) needed to create our server

We’re going to be using Express, a minimal Node.js web framework, to quickly create our local server

In addition, we’ll also be adding other packages such as axios give our sever additional functionality

From the command line (inside your project folder) run the following command:
```
$ npm install express axios body-parser dotenv
```

4. Confirm `package.json` contains the recently installed packages

Open the project in your text editor and view the contents of package.json
Confirm that the content of the file looks similar to the following:

{
  "name": "openweather-bot",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "axios": "^0.19.0",
    "body-parser": "^1.19.0",
    "dotenv": "^8.1.0",
    "express": "^4.17.1"
  }
}

5. Add logic necessary to run our server

Let’s add some code to our server to get it up and running

Create a file named index.js
Next, add the following code to index.js:

require('dotenv').config()
const express = require('express')
const bodyParser = require('body-parser')
const axios = require('axios')

// establishing the I/O port
const PORT = process.env.PORT || 3000
const app = express()

app.use(bodyParser.urlencoded({
  extended: true
}))
app.use(bodyParser.json())

app.listen(PORT, () => console.log(`App is up and running listening on port ${PORT}`))

app.get('/', async (req, res) => {
  try {
    res.json({ message: 'Welcome to Express Auth App!' })
  } catch (e) {
    res.status(e.status).json({ message: e.status })
  }
})

In the code above, we are specifying that our server should run on port 3000 (const PORT = process.env.PORT || 3000)
- This means that our the url of our server (when running) can be found at http://localhost:3000
app.get('/'...) is what Express refers to as a route handler
- Route handlers are functions that get called when the server receives a request to a specified route

The following code tells our server to return a welcome message (as json) for any successful requests sent to the root path (i.e. /)

      app.get('/', async (req, res) => {
        try {
          res.json({ message: 'Welcome to Express Auth App!' })
        } catch (e) {
          res.status(e.status).json({ message: e.status })
        }
      })

With servers, the root path represents host part of the url without anyting after the domain
- For example the root path of CNN is https://cnn.com (and not https://cnn.com/world)
- In our case, the root path of our local server http://localhost:3000

6. Run the server

On the command line run the following command to run the server
```
$ node index.js
```
Open your browser and enter http://localhost:3000 into the address bar and press enter
The welcome message should be successfully displayed

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Step 3: Set Up Node Application