What Is Node.js?

Alright, so this is not a Node.js course, so we won't be doing a deep dive into Node. I do want you to be familiar with it though, because it's a very popular environment for JavaScript and even as a front-end developer, you'll be working with NPM and to use NPM, you need to install Node.js.

So Node.js is a runtime environment. Up to this point, we've been executing our JavaScript code in the browser. Node.js is simply another environment to execute JavaScript code. It allows us to write server-side code with JavaScript. Just like other languages, such as Python, Ruby and Java. Server-side code is code that can interact with databases and the filesystem, etc.

Node is built on Chrome's V8 JavaScript engine. It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient. The way Node works is very similar to how the browser works. It uses an event loop, callbacks, promises, async/await, etc. It's essentially the browser environment minus the window object. Node does have a global object, it's just not called window,it's called global. In Node, we don't have a document object model. So it's not used for creating interfaces like we do in the browser. It's used for creating back-end applications and APIs. It's also used for creating command line tools among other things.

Installing Node.js

Installing Node is extremely easy. Just go to the Node.js website and download the latest version. Once it's installed, you can check the version by opening up your terminal/command line and typing node -v. This should return the version number. You can also check the version of npm by typing npm -v. This should also return the version number.

Let's create a folder to work in and an app.js file

mkdir node-playground
cd node-playground
touch app.js
code app.js

Running a .js file

Add console.log('Hello World'); to the app.js file.

There is no browser in this environment, so console.log() will output to the terminal.

Now let's run this file in the terminal. We can do this by typing node app.js. We can also leave off the .js extension and just do node app. You should see Hello World logged to the terminal.

Instead of just doing a hello world, let's fetch some data.

The fetch API actually was not part of Node.js up until recently. We had to use an NPM package like node-fetch or axios if we wanted to make requests.

async function getUser() {
  const response = await fetch('https://api.github.com/users/bradtraversy');
  const data = await response.json();
  console.log(data);
}
getUser();

Now let's run this file in the terminal with node app.js.

You should see the data logged to the console. Now let's run this file in the terminal.