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  Learn the basics of setting up a server with Express.
Deploying Express
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                      In this video, I'll teach you how to
setup an Express server from scratch.
                      0:00
                    
                    
                      Here's the app it has one page and
it says, I love Treehouse!
                      0:05
                    
                    
                      And that's it believe it or not,
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                      this simple app contains all the basic
components of an Express application.
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                      Express sets up its server, a server is
a program that runs on a remote computer.
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                      Its job is to wait for
HTTP requests from clients.
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                      Request is a technical term for
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                      what is happening when you
type in a URL into a browser.
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                      Your browser is making a request to
a server at the URL address you typed in.
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                      When a browser, or client,
makes an HTTP request to the server,
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                      the service brings into action
putting together a response.
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                      The development process requires you,
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                      the developer, to test and
build a web application.
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                      It's usually much easier to run an
application server on your local machine.
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                      This means you'll have both a server and
a client on your computer.
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                      You'll use a browser to test
the server in one window, for example.
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                      And then see the server
respond in another.
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                      Later, when your ready to make your
application available to the public.
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                      You'll need to deploy it to a remote
server, where other people can visit it.
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                      Deploying a web application is
beyond the scope of this course.
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                      But check the teacher's notes for
more information.
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                      Let's set up the express server now.
                      1:37
                    
                    
                      Here's my text editor with the code
I left off in the last video.
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                      We have already required
the Express module and
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                      assigned it to the variable Express.
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                      Let's create our app.
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                      To create an Express application
we can just call express.
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                      The express function returns
an Express application.
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                      Let's assign the Express application
to a new variable called, app.
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                      This app is the central
part of our application.
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                      We'll extend it throughout this course
by adding routes, middleware, and
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                      other settings.
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                      The first thing we're going to do
is setup the development server
                      2:19
                    
                    
                      using the listen method.
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                      I can give this one parameter
which is the port number 3000.
                      2:25
                    
                    
                      Believe it or not, we have an Express app.
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                      This code will create a server, and when I
run it, the server will run on my machine.
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                      And I can send it requests through
a special URL called localhost.
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                      Let's see what this looks like.
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                      I could start the app
by running node app.js.
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                      The prompt is gone because the server
is busy listening for requests.
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                      Now in my browser,
I can type localhost and
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                      then specify the port:3000 and hit Return.
                      3:02
                    
                    
                      I can see an error message from Express.
                      3:07
                    
                    
                      This is a good sign because it
means that Express is running and
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                      it's sending a response.
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                      The error is coming from the fact that I
                      3:16
                    
                    
                      have not told Express how to
respond to any requests yet.
                      3:19
                    
              
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