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Welcome back.

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In this video we're going to write our first nude application and they use the term application extremely

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loosely.

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It's just going to be a single file with some basic javascript but I'll show you how we can interact

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with node cons..

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And we'll also see how we can run a file with node.

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So those are the two objectives here.

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The first thing that we'll talk about is the node cons..

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So we've seen the javascript Council and the browser before which we can open up and we can interact

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with we can type javascript commands in the browser can do things like alert and constant log or whatever

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debugging that we want.

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Well node has its own version of the console and it's a little bit different because it's all based

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in the command line.

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We don't get the nice browser interface.

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There's no h l tools no inspector no elements because we're on the server side.

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There is no.

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Each time there is no CSSA to actually look at and interact with.

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So the node console is just a place that we can open in our terminal with a simple command and then

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we can start typing javascript commands and they'll be executed just like they are in the browser.

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And to be honest it's really not that useful.

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You might end up opening it once or twice.

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Aside from this video but I do like to show it just so that you know it exists.

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We can open it up by typing the command node and I'm actually going to show you how I can do it on my

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computer in the terminal first just so that you understand it works exactly the same way instead of

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the browser you use in cloud 9.

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So I type node and my cursor at the prompt changes would make that a little bigger.

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You can see if we get this or karet which means I'm now inside of the JavaScript console.

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So if I type something some javascript like four plus 10 I get 14 or I can do things like hello plus

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worlds just like that where I can do full javascript I could write a function if I wanted to.

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I won't do that here but I can just interact with javascript.

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It's something called a Ruppel are EPL which stands for.

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Read evaluate.

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Print loop.

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I'm a big fan of drawing comparisons between languages and between different frameworks and technologies

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.

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I'm actually going to show you Ruby's own REPL which we will never use in this class at all.

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But I just want to demonstrate so that you can see it works exactly the same way.

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So we need to get out of here and to quit.

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I can type Control-C twice and to open up the ruby cons. I type I Arbi it stands for interactive Ruby

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and now I can type ruby code in here so I'll type a really simple line of Ruby like 40 plus 9 and I

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get 49 and that's all I want to show.

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It's a place we can write Ruby in our command line we type IRP and hit enter and we enter like this

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new place where we can't type our command line things like LS or CD because it thinks those are Ruby

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variables or methods or something.

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Same thing when we go into the node cons..

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Now I'll show you how we can go over to cloud 9 and start working in the node consul here.

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It's the exact same command we just type node and hit enter or cursor changes.

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Now I can start writing server side javascript.

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So let's do something simple again.

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Well just to constantly log a bunch of letters just like that and we get this printed out.

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An important point I want to make is that a lot of the things that you're used to in the Java Sea are

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of counsel and the browser are not available here.

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We can't do something like alert if I try and do it alert.

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Hello I get an error.

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It tells me alert is not defined and that's because alert comes with the browser.

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And even though we're in the browser here remember that we're not actually in the browser so we're typing

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code in a browser but it's being run on one of cloud nine computers somewhere else on the server side

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where there isn't a browser so it just like me going here and going into Knode and typing alert something

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that doesn't exist because I'm not in the browser.

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Same thing like the document document doesn't exist at all in code.

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That's purely on the browser side.

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So none of the Domm none of those events listeners in one of the selectors.

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The manipulation all of that is only in the browser.

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None of that exists with note.

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That's all I want to show with the node cons..

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As I mentioned we really won't be using it much but it just a nice introduction to how Knode works.

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We can just start running Javascript in the terminal.

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The next bullet here is much more important which is how we can run a file with node.

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So what I mean by saying run a file with node is that we can create a javascript file.

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Call it whatever you want and fill it with javascript code and then we can execute it in the command

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line without a browser without any HD Melosi access just executed on its own by using the inode command

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to use it.

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We just type node and then a file name just like that.

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And if we hit enter it will try and execute whatever file we provided as Javascript.

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So let me demonstrate that now.

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I'm going to in my command line make a new file.

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I'll just call it hello.

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Yes so touch.

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Hello.

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Yes and now will type LS make sure it's there.

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There it is.

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Let's open it up in our editor and let's add some simple Javascript.

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So let's do a for loop for our i equals zero.

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I less than 10 I plus plus and will just do a constant alt log.

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Hello from Hello dot.

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J S.

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Just like that and we'll save it now.

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I can use the node command to execute this file to actually run this code.

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So again I type node and the name of the file which is hello.

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Yes and that's it.

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I hit enter and it executes the file for me and it constantly logs to this council here my terminal

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.

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Hello from Hello Dutch.

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Yes ten times.

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We won't be writing code like this very much what will actually be doing is stuff like this which you've

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already seen where I run node apps.

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Yes which is my file that has my server and it actually starts the server for me and it serves it on

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port three thousand and I can go visit port three thousand now because I ran after J.S. with noter as

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Noda executed the file.

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So that's what we'll be seeing.

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Use a lot more as.

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But we can also just do this or we have a for loop and it comes to that log.

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It works the same way.

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It's just javascript code that's being run the very last thing I'll show here is another parallel between

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javascript and node and Ruby so we can also create a ruby file and execute it.

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Not with the node command but with the ruby command and I'm showing this to you again.

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Not because you're supposed to be learning Ruby at all.

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You definitely don't have to remember this but I do want you to see it so that you can draw another

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comparison between node and Ruby and other server side languages.

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This is something you can do and pretty much every server side thing which so I'll go over here and

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make a new file called Hello RB and I'll open that file up.

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RB is how we make a ruby file and I'll just do something simple.

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Hi from hello.

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RB And we won't use a loop.

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We'll just do it three times and save.

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That is what Ruby looks like.

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No semi-colons or anything we don't need parentheses.

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I'll close out if there.

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And to execute that file instead of doing Noad hello.

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Yes I run ruby.

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Hello dot RB.

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And it executes my file which is Ruby code.

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It runs it as Ruby and it prints me.

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Hi from Hello dot RB.

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Three times.

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OK so that's all I want to show here.

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There were two objectives.

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One show you the node cancel which you can open by just typing node with no argument and then run a

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file with node which you can do with node and the file name and it needs to end and Dot J.S. in the

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next lesson.

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Good to have you write some javascript on your own and execute it with node