Node and the terminal

Javascript was originally meant to run only on web browsers, but this isn't the case any more.

Node.js is a tool that allows you to write and run Javascript on the server as well.

We're going to be building our web app using Node and Javascript for several reasons:

• There's no need to learn a second programming language
• Javascript is easy and quick for beginners to work with
• Tools like the GOV.UK prototyping kit are written in Javascript

Let's write a simple Javascript program in our Codeenvy workspace, and run it using Node.

When you created your app in the previous session, a folder was created with a file hello.js inside it.

Delete everything in this file so we can start afresh.

Then write a simple program:

console.log("This is a Node program")

You don't need to save the file. Codenvy will save your changes automatically.

Run a Node program

Let's run this program using the terminal.

If you just started Codenvy, your terminal should have only a single prompt in it, which will look something like:

user@6f43d9472d8d:/projects$

The /projects part of this prompt tells us that our terminal is currently looking in our projects folder.

The projects explorer is also inside this /projects folder - it's the highest folder we can access on Codenvy. ALl the code we write will be inside subfolders of this /project folder.

From looking at the projects explorer, we can see that the file we want to run is in a subfolder called my-app. We need to tell the terminal to look in this folder.

Type cd my-app and hit return.

The prompt should change to something like:

user@6f43d9472d8d:/projects/my-app$

Now run your program by typing node hello into the terminal and hitting return.

You should see your message appear in the terminal, with a new prompt appear below it:

user@6f43d9472d8d:/projects/my-app$
This is a Node program
user@6f43d9472d8d:/projects/my-app$