In this lesson you'll install Node.js on your local machine and test it to make sure everything is working.
You will need to know what operating system you have, you should be familiar with installing and running applications, and you should be able to follow instructions for installing software.
You will also need an editor where you can write programs and run them: I will be using VS Code (opens in a new tab/window).
You should install Node.js locally on your computer so you can code, test, and debug your applications before uploading them to a server. Debugging on the server can be cumbersome and difficult, but you also don't want to increase the load of your server by using it to test and debug an application!
First, download the LTS (Latest Stable Version) of Node.js: Node.js Download Page (opens in a new tab/window). If your editor doesn't have a terminal window where you can access the command prompt, you can use the Command Prompt application that comes with your operating system.
Make sure you choose the download that is most appropriate for your computer's operating system.
Once you've downloaded an installer, run it. These next instructions will take you step-by-step through the installer screens. NOTE that my screen shots are for a Windows 10 system and I was installing version 18. Yours may be different and this may result in slight differences in the screen shots.
TIP: if you forget and need to know, type which node
in your computer's command prompt window.
Before doing anything else, make sure your current Windows installation is up to date.
The script will take some time, and you might see lots of text and messages appear in your command prompt window.
When you're ready, close all open programs, including your browser. If you have any issues while the script is running, reboot your computer and then try running the script again by going to your Start Menu > Node.js > Install Additional Tools for Node.js.
After the script has finished, Reboot Your Computer. Then return to this page, for the next instruction.
You may now start the script by pressing any key while inside the Command Prompt window. PRESS THE KEY ONLY ONCE. It will seem at first like it's doing nothing, that's normal. Just be patient.
After you reboot your computer, test your installation:
node -v and then press
the ENTER key. You should see the current Node.js version
appear on the screen.
If there were any problems, go back and check the installation instructions and make sure you did everything correctly. Also, check the Node.js installation directory and see if there are files in it. If you have any issues that you can't solve, ask your professor, and be sure to provide details (error messages, screen shots, etc).
npm -v and press the ENTER key.
You should see the current version of the Node Package Manager.
If there were any problems, go back and check the installation instructions and make sure you did everything correctly. Also, check the Node.js installation directory and see if there are files in it. If you have any issues that you can't solve, ask your professor, and be sure to provide details (error messages, screen shots, etc).
Let's create a test application that we can run. I'm using VS Code, which comes with a terminal we can use to run Node.js programs. If your editor doesn't have a terminal, you can simply use your operating system's Command Prompt application.
Open up your editor and create a project directory
for this test project e.g. /testapp.
Add a new JavaScript file called app.js
and add the following code:
// app.js
// Load HTTP module
const http = require("http");
const hostname = "127.0.0.1";
const port = 3000;
// Create HTTP server
const server = http.createServer(function (req, res) {
// Set the response HTTP header with HTTP status and Content type
res.writeHead(200, {
"Content-Type": "text/plain"
});
// Send the response body "Hello World"
res.end("Hello World\n");
});
// Prints a log once the server starts listening
server.listen(port, hostname, function () {
console.log(`Server running at http://${hostname}:${port}/`);
});Save your app.js file and then open a Terminal
window (in VS Code, File > View > Terminal, or press and hold CTRL
and then press the ` (backtick) key).
In VS Code, mine defaults to PowerShell, but we want the Command Prompt: press the v-shaped icon button to the right of the word "PowerShell" and then select "Command Prompt".
If you want, you can delete the PowerShell terminal window by pressing the Delete (trash can) button on the far right, beside the "powershell" item. Do this AFTER you have opened a Command Prompt terminal window.
Make sure the prompt in your Command Prompt terminal window
shows the current location of the project you're working
on. If not, you can use the cd command to
change directories.
We will now use the npm init command to
initialize your application. Make sure you're in the same
directory as your app.js file.
At the prompt, type
npm init
and then press the ENTER key.
Running npm init initializes your app and sets
it up by asking you
several questions about your application. For any question,
you can press ENTER to accept default, which is displayed
with the question in parentheses.
Here's are some suggested answers for this test application:
Package name: the default is fine, change the name if you want
Version: the default is fine
Description: my first node.js program
(or whatever you want, or just accept the default) then press ENTER
Entry point: this should default whatever you named
your JavaScript file (e.g. "app.js"); if it's something different,
make sure that it's the name of the javascript file
Test Command: leave blank
Git Repository: leave blank
Keywords: can leave blank
Author: your first and last name
License: accept default
When you're done, it will show a JSON object on the screen
containing all the information you entered.
Instructions will appear in case you need to
go back and change anything (type n and then press ENTER
if you want to change anything: you'll have to restart by
typing npm init again), otherwise type y
and press ENTER to accept everything you entered.
Now examine the contents of your project's directory: you'll
notice a new file called package.json.
If you open it, you'll see it contains the JSON data you saw
in the terminal after you finished initializing your application.
The package.json file defines the properties of
the application and its project. This file always
lives in your project root directory. The
NPM tool needs this
file when you want to add packages to your project. You'll
learn about this in a later tutorial.
Now that your project is set up, you can run it locally by
typing:
node app
Make sure "app" is the root name of your JavaScript file.
If you named your JavaScript file "main.js", then you'd
type node main. The file extension is not
necessary.
you should now see something similar to the following in your terminal window:
Server running at http://127.0.0.1:3000/
Now go to your browser, open a new tab/window, and type:
http://localhost:3000
You should see "Hello World" in your browser!
If you reached this point without any problems, your application is working and Node.js has been installed correctly. You can now stop your application by pressing Ctrl-C in your terminal window.
As you code Node.js programs, you will likely find it annoying to repeatedly stop and restart the app after making changes to your code. If you want, you can install the Nodemon dependency: it will automatically save and restart your app when you make changes.
You can install Nodemon locally (for a single application) or globally (for all applications you write on the system).
npm install nodemon -gnodemon app.js.npm install nodemon --save-devnodemon app.js:
scripts" : {
"test" : "...",
"start": "nodemon app.js"
}Don't forget to include the comma after the "test" statement, if it's not already there.
npm start instead of "node app"