It's time to start coding.

If you've used Xpress in a project before,

you may have used Xpress Generator to create boilerplate code.

Xpress generates or provides starter code to set static HTML, CSS and image files.

Since our API will only send JSON,

the extra Xpress generated code isn't required.

It's easier for us to start from scratch.

To build our API, we'll be using a command line terminal and a text editor.

It doesn't matter which text editor you use, but I'll be using sublime text.

Let's start a terminal window.

If you haven't created a folder where you want to build this project,

create that now.

It doesn't matter what you call it.

I'm going to call mine qa-rest-api.

Change into that directory and run npm

init --yes.

This accepts all defaults and creates the package.json.

It's a fast way to create a basic package.json file.

Thoughtful configuration of a package.json file is usually a great idea,

and there's a Treehouse course on using MPM that covers this in depth.

But for our purposes this default configuration will be fine.

Next, let's install Xpress by

running npm install express@ tilde,

which means any patch release,

4.13-- save.

Once Xpress is installed, switch over to your text editor and

create a new file, app.js.

This will be our apps main file.

Let's adjust the package.json file to reflect that.

At the top of the app.js file we will type use strict,

to help us write better code.

If you'd like to know more about this, Treehouse has a workshop

on this statement, you can find the link in the teacher's notes below.

Then we'll bring in the express

module with var express is

equal to require express.

Let's use the express function to return an instance of our application.

We can store this in the variable app.

The application object is stored in the app variable.

This will let just control how the application behaves,

when restful requests are made to it.

We'll configure it shortly.

Right now, let's add a couple more lines, to get our app into a working state.

First, we'll need to specify a port to serve the app on.

Var port is equal to

process.env.PORT or

3000.

This expression will evaluate to 3000 unless we're deploying the out to

a production environment.

We won't need to worry about any of this in this course, though.

For our purposes, this will set the port to 3000.

We can start the server by calling app.listen, and

passing in the port to listen on.

If we started the app now, it would work.

But you wouldn't be able to see anything in the browser.

We haven't set up any routes.

You'd only know the sever was running,

because there'd be no error in the console.

Let's give ourselves some feedback.

App.listen also accepts a call back function as its second parameter,

which will be called once the server has begun to listen for requests.

Let's provide a callback that will lock some text to the console once the server

has successfully set up.

Express server is listening on port and

then the port variable.

Let's save this file and switch back to the terminal to start the app.

There is the message, letting us know that the server is active,

not much to see yet but it's a good start.

We'll build the Express app up in the next video.