Get Started with Node.js Service Development

0:00Hi Sean here and welcome to this skill where we're going to get started with

0:03service development in Node.js

0:05and in this first video here we're going to do something very important and

0:09that is we're going to

0:11get started by setting up Node.js as well as NPM on our local computer and we

0:21're also going to see

0:22how we can better manage versions using something called NVM. Now we'll go over

0:27the terminology

0:29etc in more detail a little bit later but to get started here just know that we

0:35need to download

0:36and install Node.js so that we can run JavaScript outside the browser right

0:41this is kind of the

0:43JavaScript runtime that allows us to do that and NPM comes bundled by it by

0:49default and NPM is a

0:51pretty interesting and very very useful tool that allows us to install other

0:56people's code in the

0:57form of something called packages into our projects so if you're not familiar

1:02with those things yet

1:04never fear we'll talk about them in much more detail a little bit later but let

1:08's just get started

1:09here by installing Node.js and NPM so what you're going to want to do is head

1:14over to Node.js.org

1:16and download the LTS that is long-term support version of Node.js now one thing

1:25to just keep

1:26in mind as we get started is that the version that you're seeing here is

1:30probably different

1:31from the version that you're going to see when you go to this website because

1:36well as versions

1:37tend to do they advance right so you'll probably see 20 point something or 21

1:43point something or

1:44you might even see 30 point something who knows but anyway we're going to

1:48download the long-term

1:50support version and you can do that just by clicking this button it should

1:54automatically

1:55download it for the appropriate operating system and once you've done that once

2:01it's downloaded

2:01completely you can click on that and that should get the installer started so

2:06let's just click on

2:07continue we're going to click on continue again and agree and then we'll click

2:13install now just

2:14before I do this before I put in my password in order to start the installation

2:18process I just want

2:19to point out that this process is pretty much the same way that you would go

2:23about updating Node.js

2:24as well all right so let's just take a short detour here and what you're going

2:29to want to do

2:30in order to follow along here is just open up a terminal you can do that in

2:34either just on your

2:36computer by opening whatever your operating systems equivalent of the terminal

2:40application is on Mac

2:42or what I would recommend is to get an IDE like visual studio code and just use

2:49the built-in

2:50terminal by going to terminal and then new terminal and that should open up

2:54something that looks like

2:55this here all right so what we're going to do here is we're going to check the

2:59current version

3:01of Node.js as well as NPM to see if you already have it installed right I'm

3:05just going to show

3:06you here that I already have this installed to confirm that this is in fact

3:10going to update

3:11Node.js and NPM for me so if I run Node.V right now what that's going to do and

3:17this is Node.version

3:18by the way this prints out the current version of Node.I have installed and

3:22then NPM-V and this is

3:24the current version of NPM that I have installed so going back to the

3:28installation process what you're

3:30going to see is that that will update the versions of both Node and NPM and if

3:35you ran those commands

3:36and just saw some sort of error saying that the command node or NPM wasn't

3:41available meaning that

3:42you don't have NPM or Node installed already well this is going to install that

3:47in the first place

3:48so let me just put in my password here and if we click install software that

3:52should run for a

3:54short bit and install Node.js and NPM for me that's going to be the new version

4:01so let's click on

4:02close now and you should see that it says Node.js version 20.10.0 again you

4:08might see something

4:09different than that exact version but in my case that's the one I'm installing

4:13and then we see the

4:14NPM the NPM version which is 10.2.3 you'll see something different there as

4:19well so let's close

4:20this now and well in my case it's going to ask me if I want to move the

4:24installer to the trash

4:26which I will and let's go back now to our terminal and what you should be able

4:31to do now is rerun

4:33Node-V and see that it's now that updated version as well as NPM-V and that

4:40will be an updated version

4:42as well cool so that's how to install Node and NPM in the first place so I hope

4:49this has been

4:50informative for you and I'd like to thank you for viewing.

0:00Cool, so that's how to install node and NPM in the first place.

0:06So the next thing that we're going to take a look at is we're going to see how

0:10we can

0:10use something called the node version manager and VM, not to be confused with N

0:16PM, which

0:17is the node package manager.

0:20We're going to see how we can use this NVM thing to manage the versions of node

0:24and NPM

0:25on our computer.

0:26Now the first question you'll probably have is why do we need to bother

0:30changing the versions

0:31of node and NPM on our computer back and forth, right?

0:35In other words, if you currently have the most up to date LTS version of node,

0:40which right

0:41now again is 20.10 point zero.

0:44Well why on earth would you ever want to change that to something like 16.1

0:49point zero, right?

0:51Or you might even want to go lower than that and go back to node 10, let's say.

0:55Well, the reason that you might want to do this, and this is very, very

0:59important as

1:00a services developer, the reason that you might want to do that is because

1:05certain pieces

1:06of code might have been written for a specific version of node, right?

1:11In other words, if you're working on an application that's, let's say maybe

1:15five years old, then

1:16chances are that application isn't going to be designed for the latest version

1:22of node,

1:23right?

1:24But you would probably want to do in that case just to create a solid local

1:29testing environment

1:30is you'd want to go back to whatever that version was and NVM can help you do

1:35that.

1:36So let's see how to get started here with NVM.

1:39Now NVM by the way is an open source project.

1:43You can find it on GitHub under NVM SH slash NVM.

1:48And if you scroll down here, you should be able to find the instructions for

1:52installing

1:53this locally.

1:55In my case, that's going to be right here, right?

1:57You can see that it's under the heading, installing and updating.

2:01And in my case, I'm just going to use this C URL command.

2:05And that's basically going to download the install script, which will run and

2:09install

2:10NVM on my computer.

2:11So I'm just going to copy this.

2:13We'll just click copy.

2:14And then I'm going to go back to my terminal and paste it.

2:18And if you hit enter, it should run for a little bit.

2:21In my case, you may see that it says NVM is already installed.

2:25Now again, you probably didn't have NVM installed already.

2:29So you might see something, you might see output that looks a little bit

2:32different from

2:33what we see here.

2:35But at this point, you should have NVM installed.

2:39So the next thing that you're going to want to test is whether or not that

2:43installed successfully.

2:45So the way that you can do that is very similar to what we did with node and N

2:50PM.

2:50And that is by running NVM dash V.

2:55All right.

2:56Now, in my case, what you're going to see is it says NVM dash V. And in your

2:59case, you'll

2:59probably see this as well.

3:01Now that's just because in general, when you run some kind of install script

3:05like we just

3:06did, you actually need to either restart your terminal or manually source,

3:12whatever you

3:13just installed in order for those changes to take effect and be able to use

3:16that new

3:16command.

3:17All right.

3:18So we're going to do that.

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0:00All right, so now that we've seen the basics of installing node JS and NPM and

0:04we've also seen how to use the node version manager to switch between versions

0:10of node and NPM pretty rapidly.

0:13The next thing that I want to show you is how we can run snippets of node JS

0:17code, right? That is JavaScript code.

0:20Well, two ways really that we can run JavaScript code in the terminal.

0:25Now the first way here and this way is very, very useful when you want to test

0:29out snippets of code, you want to make sure that you understand the syntax of

0:34JavaScript, right? Sometimes it happens to me where, you know, I get mixed up

0:38with the syntax and I run into some kind of syntax error.

0:41So I want to actually run that piece of JavaScript code in the terminal to try

0:46and play around with it and see if I can get it right. Well, you can do that

0:51all by opening up the node JS terminal and you can do that just by running node

0:57with nothing after it in your terminal.

1:00And by the way, in case you haven't caught on to this yet, I'm going to be

1:03using visual studio code for all of these demonstrations. If you want to

1:06download that, your best bet's just going to be to Google download visual

1:10studio code, and that should take you right there.

1:14So anyway, once you've done that, again, you can open up a new terminal here by

1:18going to terminal new terminal. That should get you to where I am right now.

1:22So let's run the node command now. And what you're going to see is that's going

1:27to say welcome to node JS V 20 point 10 point zero, right? That's the currently

1:33active version of node JS that we installed using NVM.

1:38And instead of the normal terminal, what you can see here is this is basically

1:43just a little terminal that we get to run node JS snippets in right so

1:48basically again JavaScript code.

1:51So first things first, let's just try console.log Hello.

1:56And what we're going to see there is sure enough, it'll print out hello to the

1:59console and underneath that you're going to see this undefined thing.

2:03Basically, all that that means is this is the return value of whatever

2:08statement, whatever code we just ran in the terminal. And since console.log

2:13doesn't return anything, that's why we're seeing undefined.

2:17All right. Cool. So anyway, now that we've, now that we've opened up the node

2:22JS console, let's try something a little bit more interesting.

2:26And I really want to tie this back in with the whole node version manager thing

2:30and working with different node versions.

2:33Let's try something here that's going to be a little bit different depending on

2:37the version of node JS that we currently have active.

2:41So what I'm going to do is I'm going to say const util equals require util. All

2:47right.

2:48And then I'm going to say const read file promise equals util.promise if I, and

2:58then I'm going to call that on require FS dot read file and the read file is on

3:06require FS.

3:08And then basically what this is going to do is it's going to convert this

3:14normal read file operation, right?

3:17This read file function on the FS package into a promise, right?

3:22It's going to convert it from a callback based function to a promise based

3:26function.

3:27And the thing about this is if we run it here, it should work just fine, right?

3:31We can now say read file promise, and then we'll pass some kind of code into it

3:37and you might want to actually create a file that we can read here.

3:40And by the way, what I did here is I just created a new directory called JS NSD

3:45example code.

3:47If you just create a new file here and call it something like my file dot TXT.

3:53And then we'll just add something to this file. We'll say hello from a file.

3:58All right, well, we should be able to read the contents of this file now by

4:03saying read file promise my file dot TXT.

4:06And we'll add the UTF-8 encoding there.

4:11And by the way, if you're not familiar with these functions, I'm not going to

4:13be going over the specific details of doing things like reading files and Node.

4:17js, etc.

4:18That's something that you can find by taking a look at one of my other Node.js

4:22basics courses.

4:24So feel free to check that out. But anyway, what this is going to allow us to

4:29do now is say dot then.

4:31And this will give us access to the contents of the file, which we can just log

4:35out to the console.

4:37We'll say something like contents, and then we'll say contents or console dot

4:41log rather.

4:42Contents, okay. So if we close that function off and hit enter, sure enough

4:48what we'll see is after this promise thing, which is the return value of read

4:53file promise.

4:53Etc. We see that it prints out hello from a file to the console.

4:58Now where I'm going with all of this is this code worked because we have the

5:03current version of Node.js that we have.

5:07However, if we were running a different version of Node.js, things wouldn't

5:11work out quite as well.

5:13All right, so what I'm going to do is exit out of the node terminal, which you

5:16can do with control C, pressing that twice.

5:20That is, and I'm going to change the version of Node.js that we're using to

5:24something quite a while back.

5:26So actually, what we're going to do is we're going to say NVM LS so that we can

5:30see the old old versions of NPM that we can install or of Node rather.

5:35So let's install Argon. This one is by all appearances, the oldest one we're

5:39able to install.

5:40So let's try saying NVM install. We can just use LTS and ups I spelled install

5:46wrong LTS slash Argon.

5:49And that should install version 4.9.1, very old version, and basically set that

5:55as the current version of Node, which we can verify by saying Node-V.

6:01And sure enough, we see 4.9.1.

6:05So let's open the terminal back up and we're going to try doing the same thing

6:08that we just did, right?

6:10Promissifying and reading a file, and it's just not going to work.

6:14You'll see how exactly in just a minute, but let's just open up that terminal

6:18by saying Node.

6:20And if we try running our code again, and by the way, you can do that just by

6:23using the up arrow, let's scroll back up to this const read file promise equals

6:29util.promissify thing.

6:31Now, one thing that's interesting to note is that you don't actually need to

6:35import util here because it's just included in the scope by default.

6:41But if we try and run this file, what we'll see is that it says util.promissify

6:45is not a function.

6:47Now, the reason that you're seeing this error here when the code worked before

6:51is because in this older version of Node, there was no function called promise

6:56ify on util, right?

6:58It hadn't been added yet.

7:00Whereas as we already saw in a more recent version, a very recent version, in

7:04fact of Node.js, that function worked just fine.

7:07So this is just one example of many different pieces of code that will either

7:12work slightly differently or not at all in different versions of Node.js, which

7:19again just kind of underlines the importance of using the correct version and

7:24node and being able to switch between those versions with NVM.

7:28So anyway, now that we've seen how to run code in the Node terminal and just

7:32some implications of running code under different Node versions, let's switch

7:37back to the later version.

7:39And we can do that by saying NVM use and we can use its alias here.

7:43We'll say LTS slash iron.

7:46And that will give us 20.10.0.

7:49And by the way, in case I didn't mention this, I don't think I did.

7:52Another advantage of using these nerdy aliases here is that it will actually

7:57give you the latest update on a given version branch.

8:02Right, so if you want to picture the way that Node versions work like this,

8:07basically the way that they work is for any given Node version, let's say four,

8:12five, six, all the way through.

8:15Here we have 18, 19, 20. Well, obviously each version sort of builds off of and

8:22improves the one before it, right? So 20 builds off of 19, 19 builds off of 18,

8:28all the way down the chain, right?

8:31However, because of the fact that given a specific version of Node JS, there

8:35are many, many applications that are dependent on that version and require that

8:41exact runtime in order to run correctly.

8:44Each of these versions is kept around and improved just sort of as an

8:49independent branch. Right, so even after Node JS version 20 is released, there

8:56's still going to be changes and improvements on 18, 19, all the way through.

9:00So by using those aliases, right, by referring to LTS slash iron or LTS slash

9:08Argon or whatever, that's going to bring you to the latest release on that

9:15branch.

9:16So in other words, you're not going to need to keep your eye on the Node JS

9:19news for when 20.10.1 comes along. You can just refer to it by its alias and

9:24that will make sure that you're using the latest version in that branch.

9:29So anyway, now that we've switched back to a modern version, a much more modern

9:34version of Node JS, that is, let's run another piece of code here.

9:39And this is going to be basically just a command that we type into our terminal

9:43. So what this command is going to be, it's going to be at node dash E.

9:48And then in double quotes, we're going to say something like console.log. Hello

9:53. All right. Not a not the most exciting piece of code around, but there is a

9:56point here as you'll see.

9:58And if we hit enter, what we're going to see is that sure enough, hello gets

10:01printed out to the console. Now this node dash, anything, what this does.

10:07And the dash E stands for execute, by the way, is it will execute whatever code

10:12we have in this string. So this is basically a way of running individual small

10:18pieces of Node JS code, right?

10:21So this is a server side JavaScript code without actually having to open up a

10:27node terminal and type commands into there, right, without having to open up

10:31the read evaluate print loop, our EPL, as that's often referred to.

10:36All right. Now the reason that I'm showing you these things, right, how to use

10:40node dash E and how to use the node terminal in order to run just basic

10:44snippets of JavaScript code is because these are two very useful tools

10:50for testing the web servers that you create with Node JS, right? So what we're

10:55going to see very shortly is how to create a basic server using Node JS as well

11:00as several Node JS libraries, such as Express and Fastify.

11:06Well, if we have a server running here that we want to test, we need some way

11:10of sending requests to that server so that we can see how that server behaves

11:15and what data it responds with.

11:18Well, there are obviously lots of options for what we can have over here on the

11:22client side sending those requests. Well, in many cases, the easiest option is

11:28to have that thing on the client side be another piece of JavaScript code,

11:33right?

11:34So using what we just saw, if we have a server running over here again, and we

11:38want to send a request to it, we can just write a little piece of JavaScript

11:43code that will actually send a request to that server, and we'll be able to see

11:48there right in the console, what that response was, and we'll be able to do

11:52things like manipulate the response, look at it in more detail, etc.

11:56In that case, we just have this little console thing that's making that request

12:01and basically processing the response that we're getting.

12:05Anyway, to make a long story short, the reason I showed you those two ways of

12:10executing server side JavaScript code is that frankly they just make great

12:14testing tools.

12:16So anyway, I hope this has been informative for you, and I'd like to thank you

12:19for viewing.

0:00All right, so at this point, we've got pretty much everything set up and we've

0:04covered pretty much all of the topics that are going to lead us up to the main

0:09feature of this section.

0:11And that is creating a simple web server using Node.js.

0:16All right, now a server is really going to be the main unit that we end up

0:20building our services out of, right?

0:23So really all that a server is is a program that sits there and listens for

0:28requests, right?

0:30These are incoming messages, if you will, from somewhere on the Internet, right

0:36?

0:36Somewhere across the Internet.

0:38And when the server receives a request, it's going to execute some sort of some

0:43piece of code and it's going to send some sort of response back to whoever sent

0:49that request.

0:51Now the cool thing, and this is something that we'll get into later, is you can

0:55actually have an application that consists of multiple servers, right?

1:01So you could have, let's say, three or four or a hundred servers, and these

1:07servers can actually talk to each other as well as to external clients, right?

1:13So in other words, this server here might get a request from some client, and

1:18in order to complete that task, right?

1:21In order to do whatever it is that this client wants it to do, it might have to

1:25communicate with these other servers.

1:28So it might have to send its own request to this server here, that server might

1:32respond, then it might have to send a request to this one here.

1:36This one then might have to send a request to this one, and so on and so forth.

1:40So as you can see, you can create some very interesting structures here, all

1:45right?

1:45And there are benefits to structuring your applications like this versus just

1:50having a single server that contains all of that functionality.

1:55And that's something, again, that we'll talk about later, but I just wanted to

1:59show you kind of what a server is and how it fits into this whole idea of

2:04service development in Node.js.

2:07So, and by the way, this server here at some point, if it all goes well, would

2:11send back a response to the original client.

2:15Cool. So anyway, with all that said, it's obviously going to be very important

2:20that we know how to set up and run a basic Node.js server.

2:25So let's take a look at how to do that.

2:28Now, obviously it's possible to set up a server just in your terminal.

2:32You could do that if you wanted to, right? You could just run the node command

2:36and then set up and run a server from here.

2:40However, that's really not the best way to go about things because, well, you

2:45're probably going to want to have the code for that server in a reusable format

2:51, which is why not surprisingly, we generally create our servers inside a

2:55JavaScript file.

2:57So let's create a new file here. And again, I'm just, I created this JS NSD

3:02example code directory. And you might want to do that as well.

3:06Just create a directory to hold all of your code. And let's create a new file

3:10inside of here. And we'll call this something like core node server.js.

3:17But the reason that I'm specifying core node server is because, as we'll see in

3:22later skills, there are plenty of frameworks in Node.js that greatly simplify

3:29the task of creating and running a server.

3:33But, you know, just to start at the very beginning here, we're going to see how

3:37to create a server without any other frameworks, without any other libraries.

3:42And, well, this is basically what all of those frameworks and libraries are

3:45built off of in the first place. So it's probably a good idea to at least see

3:49how this works.

3:50So really the main thing, the main package that you're going to be using when

3:56you're creating a core node server, right, with only the node.js core packages

4:02is HTTP.

4:04So what we're going to do is we're going to say const HTTP equals require HTTP.

4:10All right. And then what we're going to do is we're going to create a server by

4:16saying const server equals HTTP dot create server.

4:19Now, not surprisingly, this create server function is going to create a server

4:24that will then be able to start up and that will basically just sit there and

4:28listen for requests.

4:30So the way that we start up a server is by saying server dot listen, and we get

4:36to specify something called the port. Basically, this port is basically just a

4:42number that allows us to distinguish between different connections or different

4:48services

4:48as we'll see later on that are running on the same computer. So as you'll see,

4:52when we actually create applications that are made up of multiple servers, we

4:57're going to need to have this port number, which for now we'll just use

5:01something like 3000, which is a pretty commonly used port number at least for

5:06development.

5:06We're going to have to come up with different numbers for each of those

5:09different servers, right, so we might need to have one server running on port

5:143000, one server running on port 8000 and one server running on port 8080. Let

5:20's say.

5:20All right, so anyway, once we've started our server, we're probably going to

5:24want some sort of output in the console in order to let us know that the server

5:28has started up successfully.

5:30And the way that we do that is by passing a callback function as the second

5:35argument to server dot listen.

5:38And that's going to look like this. We're just going to use a arrow function,

5:42and we'll say console dot log, and we'll print out something like server is

5:48listening on port 3000.

5:50Okay, and that is pretty much all we need to do except at this point our server

5:54isn't actually going to do anything right we've told our server to start

5:58listening but obviously, you know, when a server receives a request as we said,

6:04right, when we have our server and a request comes in,

6:07we're going to want to have some sort of code that gets executed and sends back

6:11a response to whoever the client was that's a really poorly drawn computer

6:16there but anyway you get the idea.

6:19So the way that we do that, and this is going to be a very popular way of doing

6:23things in case you're not familiar with working with no JS, we're going to

6:28define another callback function and pass that to HTTP dot create server so

6:34here's what this is going to look like we're just going to have

6:36a simple callback function. And inside here will print something out to the

6:40console by saying something like console dot log.

6:43I received a request.

6:48Okay, and that's all we're going to do right now. Now this is not really a

6:52complete implementation for this callback function because as you'll see in

6:57just a minute, it doesn't send back any kind of any kind of response to the

7:02client.

7:03We'll see how to do that in a minute as well. But nevertheless, it will do

7:07something when it receives a request. So what we're going to do here is we're

7:12going to run our server that we just created by saying node core node server

7:18dot JS, right, this is going to run our server file.

7:21And if we hit enter, what you'll see is that it prints out server is listening

7:25on port 3000, and then it just sort of sits there, right? Well, the reason that

7:30it's doing that is because generally the server programs that we create will

7:35run continuously, right, so unlike regular node JS scripts or scripts of any

7:42other programming language for that matter.

7:44When we create servers, that server is just going to run continuously, usually

7:49until we manually stop it or it crashes, let's say.

7:54So right now, again, our server is just sitting there, waiting for some sort of

7:59request to come in.

8:01So let's test this thing out now by sending a request to it.

8:05Now, the probably the easiest way to test this out is a way that we saw in a

8:11previous video here, and that is to just open up a new terminal and go to the

8:17node, reevaluate print loop.

8:20All right.

8:21And then we're just going to use the same HTTP package here, right, the same

8:26HTTP module to make a request to our server that's currently running.

8:31So here's what this is going to look like. We're going to say const HTTP equals

8:36require HTTP.

8:37All right.

8:38And now that we've imported the HTTP package, what we're going to do is say

8:44HTTP dot request.

8:46And the URL that we're going to send this request to is the first argument that

8:50we passed to this function.

8:53And that's just going to be in our case here, HTTP colon slash slash local host

8:59, because this server is running locally on our computer.

9:04That's what local host refers to generally.

9:07And then we have this this colon 3000 thing that refers to the port number.

9:12So again, if we had multiple servers running on our running locally on our

9:18computer, we could change this port number to 4000 5000.

9:228000, 8000, whatever, in order to refer to different services, right, in order

9:28to send our requests to different servers on our computer.

9:32So we're just going to send it to local host 3000 right now.

9:36And basically, that's all that we need to do, right.

9:40And in order to actually send this request, what we need to do is add dot end

9:44on it with parentheses after it.

9:47So basically what this is doing, it's creating this request that it's going to

9:50send to this address, right, this URL.

9:53And then by saying dot end, that's actually going to send it.

9:57So let's hit enter here.

9:59And if we go back to our other terminal now where our server is running, sure

10:03enough, we'll see that it says I received a request.

10:07Now again, this server that we just created isn't really fully functional yet

10:12because it's not sending back any kind of response to the client.

10:16And that's the next step here.

10:18You see, in order to send back a response to the client, we have to actually

10:23use an argument that's going to be passed to this callback function

10:28automatically.

10:29And there's actually two of them.

10:31One is called request and one is called response.

10:33They're usually abbreviated R E Q and R E S. And the R E S one, the response is

10:38what we're interested in here for the time being.

10:42We'll talk about the request argument a little bit later.

10:45But anyway, what this is going to look like is we're going to print out, I

10:48received a request, but then after that in order to send a response back to the

10:54client, right, in most cases, the client will actually think that something

10:58went wrong or think that there was some sort of error if we didn't send back a

11:02response.

11:03What we're going to say is we're just going to say res dot end and we get to

11:07basically pass whatever we want here.

11:10And that will be sent back to the client back to whoever sent the request as a

11:15response.

11:16So let's say response dot end.

11:18And in here, we'll say something like hello from the node JS server.

11:25And if we restart our server now, which we do have to do in order for that

11:29change to take effect, all right, so you can stop it by saying, control C.

11:34And then we just run our server again by saying node core node server.js.

11:40And if we go back to our other terminal now, what we can do is we're actually

11:44going to run this same kind of function again, HTTP dot request dot end.

11:49But in order to actually allow ourselves to see the response, we're going to

11:55add a callback function to this HTTP dot request function.

12:00This is going to be the second argument here.

12:02And basically what this is going to look like is we're going to say response.

12:07All right, so this is the argument that gets automatically passed to this

12:11callback function.

12:13Again, callback functions are a big thing in node JS.

12:16They basically just give us a nice way to handle code in an asynchronous manner

12:22.

12:22And what we're going to do is we're going to say response dot pipe.

12:25And then we're going to say process dot standard out.

12:29Now, basically what this is going to do, don't worry too much about this res

12:32dot pipe thing.

12:34We'll talk about that in more detail later as well as process dot standard out.

12:38But this is just going to take whatever response we get back and print it to

12:42the console.

12:43So let's just hit enter here.

12:45And sure enough, what we see is that it says hello from the node JS server,

12:50right?

12:50It just prints that right to the console there.

12:53And if we go back to our other terminal here, we'll see that our server sure

12:56enough printed out, I received a request.

12:59So that's the basic idea of creating a simple web server using the node JS core

13:06.

13:07And really all that our server is doing right now is it's just handling all

13:12requests that come in by sending back hello from the node JS server.

13:17And this might seem a little bit simplistic, but really the functionality that

13:20you see here is the foundation of building services in node JS.

13:26So anyway, I hope this has been informative for you and I'd like to thank you

13:29for viewing.

13:30[BLANK_AUDIO]

0:00All right, so now that we've learned the basics of working with Node.js and we

0:04've seen how to create a simple HTTP server

0:07It's time for us to solidify what we've learned by doing a challenge now

0:12The challenges in this course are going to be a little bit different than some

0:17of the challenges I've done in other courses

0:19Because I'm gonna be trying something new which is something called code spaces

0:24now code spaces in case you've never heard of it

0:26It's still at the time of recording a fairly new

0:29Fairly new thing code spaces are basically an integrated version of visual

0:36studio code that you can use directly on

0:39GitHub it's they're they're really cool. I think you're really gonna like it

0:42and the

0:43The reason I'm using these is because it will allow you to immediately

0:47Access the code that you'll need for the challenge without having to type it

0:52all out yourself

0:53So anyway, let me just show you real quick how to access the code you're going

0:56to need basically what I've done here

0:58Is I've taken the code that I typed out

1:00previously this basic server code and I've created a new GitHub repo around it

1:06and

1:06Basically just pushed all that code up so you can see that there's core node

1:10server and this my file that TXT thing that we

1:12Used for testing purposes previously and if you click on this file you can see

1:17that it contains all that code

1:19Now what you're gonna need to do for this challenge is you're gonna want to

1:24open up a code space on this

1:25Specific commit right what's gonna happen is as I create more and more skills

1:31I'm gonna make changes to this to this repo so you're gonna need just this

1:36commit here

1:37So what you're gonna want to do is click on the commits list there may well be

1:42many more than just one commit by now and

1:46I'm going to click on the server built with no JS core

1:49This is the commit that you're going to need to access here in order to do this

1:55challenge

1:56And actually instead of clicking on that sorry

1:58You're gonna want to click over on this little button here that says browse the

2:02repository at this point in the history

2:04So if we click on this what that's going to do is

2:07Well, if you were seeing something different than what I had here

2:12you should be seeing the exact same thing right now with these two files and

2:16What you can actually do now is in order to open this up in a in an online

2:22editor code spaces

2:24That is you can just click on code and then you should see this button that

2:29says create code space on blah blah blah blah blah

2:31This this long commit hash right that's going to create a code space at this

2:37exact point in the project's history

2:40So that might run for just a minute and then you should see something that

2:44looks an awful lot like visual studio code

2:46Appear in your browser and you can personalize this a little bit as well in

2:51case the

2:52Bright color is hurting your eyes. You can always click on choose the look you

2:56want and then go to browse color themes

2:58And I believe the one that I usually use is um dark plus so there we go

3:04That's much easier on the eyes and oops. I didn't want that one

3:07Let's go back to there and select dark plus again accidentally click something

3:12Uh, so cool at this point you have visual studio code

3:16Basically a version of vs code running in your browser and you may want to zoom

3:22in a little bit as well

3:23There we go just to make it a little bit more readable

3:26and um

3:27What you can do now is because you have both core node server and my file that

3:32txt

3:32You can just run that directly in your terminal here

3:37By saying node core node server

3:40Dot js and then you'll see server is listening on port 3000 now an interesting

3:46thing is since this

3:47Visual studio code is

3:49Not running locally on your computer, right?

3:52It's running presumably on one of github servers

3:54Things might be a little bit different when you go to run the challenges

3:58Um, so what you can actually do it says your application is running on port

4:033000

4:04And uh, if you say open in browser, what that's going to do is it's going to

4:09open a new browser window

4:10That will actually make a request to your server

4:14Uh, through proxy that github sets up, right? So you'll see hello from the no

4:19js server actually displayed in your browser

4:22Um, and really all that's happening here is your browser is

4:25Acting as the client instead of just running a piece of no js code in a

4:30terminal like we were doing before

4:32Now you can also test this thing out by the way

4:35Just by, um doing the same thing that we did before and that is opening up a

4:39new terminal and just saying node

4:41And then uh, you can say something like const hdtp equals require hdtp

4:47All right, and then you can say hdtp dot request and you can send that to hdtp

4:53colon slash slash local host

4:553000

4:58And in order to uh, intercept the request and print it out to the console

5:02You can just say response dot pipe and send that along to process dot standard

5:08out

5:08And oops, let's uh make sure we type that correctly

5:11All right

5:13And then we can say dot end and sure enough we'll see that that has hello from

5:17the no js server printed out to the console as well

5:20So there's no difference if you're going to test it from here

5:22It's only if you're going to uh test it later on from outside

5:28this uh basic visual studio code refracing from outside this code space that

5:32you're going to need to

5:33Um, uh, worry about that and i'll walk you through that when we get there

5:37So i'm just going to close this other browser window there or browser, uh tab

5:41there for the time being

5:43And that's all you should need to know in order to actually uh run this

5:46challenge

5:47So let's actually get down to what this challenge is going to be

5:51And um in order to avoid confusion later, let's just stop our server and uh, we

5:56'll clear out our browser

5:58Or clear out our other terminal as well

6:00What we did previously is we saw how to set up a very simple HTTP server that

6:05sent back

6:05Uh, a pretty useless message saying hello from the no js server

6:10So your challenge here is going to be to make this server do something a little

6:14bit more useful

6:15And send back the current date and time

6:19All right, so in other words

6:20You're going to write that logic inside this callback function

6:24And send back a string to whatever client sent the request

6:27Telling them what the date and time is and uh, in case you don't know how to do

6:33that in javascript

6:34Feel free to google that

6:35All right, so that's your basic challenges to rewrite our server here

6:39So that it will um, send back the date and time instead of just a, uh, useless

6:44string

6:44So, uh, that should take you maybe about a minute or two to complete this

6:48challenge

6:49And once you've made those changes definitely make sure that you actually test

6:54your server out

6:55So that's your challenge in the next video. I'll show you how I solved it

6:58So I hope this has been informative for you and I'd like to thank you for

7:01viewing

7:02[BLANK_AUDIO]

0:00All right, so hopefully you've given this challenge a try.

0:03What I'm gonna do in this video is walk you through

0:05how I solve this challenge.

0:06Really, all that you had to do in this case

0:08was rewrite the logic that gets executed

0:11when the server receives a request

0:15so that instead of just printing something out to the console

0:19and sending a string back to the client,

0:22it actually got the current date and time

0:25and sent that back to the client.

0:26So what this looked like is we had to start off

0:29by getting the current date and time.

0:33And in JavaScript, the way that you do that

0:35is by saying new date rather, new date dot.

0:40And then you could either say to date string

0:44or to locale date string,

0:45which takes into account the locale that you're currently in

0:50and prints out the date in the format that you're used to seeing.

0:54So basically we could just take this

0:56and assign it to a variable.

0:58I said const, date and time equals new date dot to local date string.

1:03And in order to send this back to the client,

1:08all we had to do was say response dot end

1:13and in a back tick string here,

1:15which would make the date and time easier to insert.

1:18Nicely, we could say the current time is

1:23or the current date and time is.

1:28And then we could insert date and time like so.

1:32And oops, that needs a dollar sign before it.

1:34There we go.

1:35And that should be all we need to do

1:38in order to modify our server for that purpose.

1:41So let's try running this thing now

1:43and testing it out.

1:44What we're going to do is run our server with node core node server dot JS.

1:49And sure enough, we see server is listening on port 3000.

1:53This thing shows up down here as well.

1:55And we'll do things like make it public a little bit later on in the course.

2:00But let's open up another terminal.

2:03And actually, I did this in reverse here.

2:05We'll just open up whatever the other terminal is that we're not currently

2:07using.

2:08And we're going to run node inside of here.

2:11And then what we'll do is we'll say

2:14the same thing that we did before.

2:16We can just say const HTTP equals request.

2:20Oops, let's try that again.

2:21There we go.

2:22Not request require rather.

2:24HTTP.

2:25And then we can say HTTP dot request.

2:29And then we'll send it to local host.

2:32Oops, HTTP colon slash slash.

2:34That is local host 3000.

2:38And for the response, we'll want to print that out so that we can see it.

2:42We'll say response dot pipe and pipe that to process dot standard out.

2:47And then we can say dot end in order to send that request.

2:50So if we hit enter, sure enough, what we'll see is the current date

2:54and time is.

2:55And oops, that's actually just the date string.

2:57So let me get the time as well.

2:59And actually, what you can do for that is you can say, instead of too local

3:03date

3:03string, which just gives you the date, you can say to ISO string.

3:08And let's just save that and rerun our server here.

3:11We're going to stop it with control C and restart it.

3:15And let's go back now and try running that same command.

3:18You can actually just get up to it again, without having to type it all out

3:22by using the up arrow.

3:23And there we go.

3:24Sure enough, we see that we have this ISO string.

3:27It's a little bit hard to read.

3:28So if you wanted to play around with the formatting there as well, you could

3:31always do that.

3:32But we see that sure enough, 2023, 1125.

3:35And then we have the time here as well.

3:38So anyway, that is the basic solution to the challenge.

3:42Congratulations if you figured that out.

3:44And in case you're looking for other things to do, other things, other ways to

3:49practice this core node server functionality,

3:53I've left a list down below of other potential fairly simple projects that you

3:58could implement.

3:59So I hope this has been informative for you.

4:01And I'd like to thank you for viewing.

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