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Welcome back, ladies and gentlemen, into this lecture, we're going to talk about JavaScript types

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and there are seven different JavaScript types.

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Now, we're not going to cover all of them, but we're going to cover the first three no strings and

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booleans.

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Then in future, we will cover undefined, no symbol and objects in Y say, in future.

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Well, because for these four or five, six and seven, we need to have a background knowledge for in

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order to understand them.

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That's the only reason I don't want to confuse you from the beginning of this section.

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OK, now in order to follow me in this section, it is preferrable for you to have installed a text

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editor or a code editor.

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So I'm going to use voice code now.

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How you can install viscose so you can type on Google vehicle and code that visual studio, that will

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be the link that you want to visit.

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And inside here, you can download for your for your operating system so you can install it for me.

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I have already done it.

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And it's for Mac and you.

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If you're using windows, it will here, it will say for Windows.

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OK, now some students will ask me why I'm telling you this again, because in some of the other sections,

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I would probably say that you need to have installed a.

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Well, the thing is that the students will skip some of the sections in when they see me using something

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they haven't installed on their machines, they will start asking me questions.

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That's the only reason now why I'm using Vasko throughout this course, because it's very lightweight

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and it's very supportive.

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It has a lot of extensions here.

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Right.

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And also building it, you can run and debug and it's Intellisense.

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Very good.

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Now, you don't know.

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You don't need to know everything of this.

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OK, so why I'm going to use this code one more time is because there I will want to write JavaScript

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code here and save it in files.

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So those files after that, you can access them and you can change them.

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You can modify them, you can refresh your memory.

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You can do your exercise.

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That's the only thing.

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Now, one more thing that I want to show you is that you can run the JavaScript code even in your browser.

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Right.

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So if you open Google dot com and if you inspect it, you will see here a console tab.

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So if you go in the console tab now here you can write a code.

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For example, let's do basic mathematical operation nine plus six.

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That will be 15.

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Right.

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So you need to hit, return or enter because before it was light blue, four in my browser, for example,

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here, this is 13.

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But when I hit return on Macs or enter in windows, you will see this as a dark blue.

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OK, that is pretty much what I want to show you.

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Now, how are we going to do this?

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First things first, you need to have on your desktop to see to download these JavaScript Genesis file

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folder and in this directory here, I do have two things.

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Final will contain all of those lecture's exercises, solutions.

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But Starger will be empty.

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And I'm going to do I'm going to start with the starter.

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Right.

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But you will need the final one in order to see all of the exercises.

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So I want you after each and every lecture to go there and to see if that lecture has exercise and do

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them.

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And also there are solutions if you are stuck.

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Very good.

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I'm just do I mean, shift your folder on your desktop.

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So mine is on desktop.

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So here I'm going to say open folder.

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Good.

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I'm going to navigate to desktop starter hit enter.

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This is how you use this code.

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Nice.

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So inside here we're going to create a file.

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There is a plus symbol or right.

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Click new file I'm going to use here.

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I'm going to create index that HTML file in here, start typing doc he tap and it will give you the

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entire document.

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Now the title you can change the title, whatever title you want.

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For example, just put it here.

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Java script fundamentals.

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Very good.

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And in the body you can type each one tack and say OK, say again, JavaScript, Genesis.

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Fundamentals are very good now.

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That is pretty much what I want you to have in this file, so I'm going to use this one right.

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And so probably you need to install the live server.

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So go here on the extension step in heat like server.

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And here it is, lunch mine has already been installed, but you will see here install.

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Right.

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So install that one.

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If you need to close your viscose, close it just to restart it.

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And you're good to go.

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So I need this live server.

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So here you can actually activate this life server, go right.

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Click and open with live server or there is a shortcut.

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Good.

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Just open with life server and here it is, JavaScript Genesis Fundamentals.

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This is coming from the H1 track that we wrote.

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OK, now what I'm going to write here, another file.

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Let me do it like this.

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And you called lecturer.

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Um, yeah, lecture one, dash one, that is this how are we going to name our lectures?

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And this lecture is a JavaScript file.

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Now, I just want to tell you that we do have a couple of ways how we can write JavaScript in our browser.

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And the first thing is that we can do external files.

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This is called external files.

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But in order for this to work, I am going to tell you that we need to load them here.

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So first we need to say script and we need to close this one.

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Now, in the script that we have source and the source will be our current directory, not forward slash.

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And that will be lecture one.

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That J is very good.

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And also we need to specify the type.

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So Browser will know what to expect that that will be text and forward slash JavaScript, JavaScript

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cuz now our JavaScript file, external JavaScript file is connected with this file here.

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Right.

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So there's other ways, but they're very basic.

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I'm going to tell you in future you don't have to worry about it.

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Right.

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OK, now about JavaScript times, you can make a comment in JavaScript to forward slash and type JavaScript

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types.

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OK, now the first one that I want you to know is called the number.

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So why is this very useful?

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OK, this is one of the basic ones.

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So with numbers, we can do basic math operation, for example.

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We can just calculate how much is three plus seven.

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OK, just do it.

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Three plus seven semicolon and put a semicolon there.

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Save it.

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Or if you don't see me.

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So here there is a bubble that means they have and save it.

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No.

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So now you need to also before checking your code, you need to save it.

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So control s or command as in as is or control as in windows and that will save the file.

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So there is no bubble there.

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Right.

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But now if you go here and if you refresh if you.

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Right.

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Click inspect.

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In the console, there is nothing there in why's this before, remember, we just rode three plus seven

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and it would give us the result.

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But now I'm using the direct console here, this terminal here.

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But in code, I don't have access to that.

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So if you if you want to print out something to the browser here, which I can just delete it here,

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let me just delete like that.

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OK, so I need to write console console that log and put this one in brackets.

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Now save it again and just go back here.

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And here it is.

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You do have 10 actually with live server.

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You don't have to you don't have to refresh because it's going to work out comedically.

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So with numbers we can do basic maths operation.

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What else we can do?

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Let's try something else.

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Let's cancel the lock loops console.

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So we use console the log every time we want to show something.

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Right.

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So ten minus nine, save it.

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Right.

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A couple of them console that log.

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Not long, and here we are going to say 10 times three.

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So let's divide something on the log, divide 20.

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Divided by five.

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OK, now save it, go back to your browser and you will see that I have 10 one 30 and for good for it's

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coming twenty divided by five.

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It's for ten times three is going to be thirty.

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And this will be one.

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And the first one will be ten.

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OK, so if you want to write it, we can achieve the same thing here.

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Ten times three it will be equal.

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Thirty, ten minus nine it will be one in twenty.

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Divided by five it will be four in.

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How does this leave.

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A server is working.

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It will create a new URL.

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This will be our local localhost actually our local machine and it will give us a port.

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Maybe you're going to have a different port.

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It doesn't matter in the HDMI is the file that I've created.

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This one so you can hear here, exclamation mark, save it again.

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And there you go.

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The changes are already there.

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And plus everything that we have done here in this is also printed out here.

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Right.

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OK, now, so let me quickly show you something else so we can do more complex operations like using

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brackets or small brackets.

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So console's along, for example, more complex operation is five minus two that will be multiplied

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by by four minus.

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Let's say to right, maybe that's not a good example, let's do it here, six, six, minus two.

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So how this will work?

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Well, if you know, Max, these first six minus two will be calculated, it will be four, then four,

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minus two.

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It will be calculated, it will be two.

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And after that, whatever it's in the brackets, we can multiply it right.

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So we can just six minus two, four times four.

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So we can't we first need to work in the brackets and after that, just to calculate this one.

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So save it.

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So this should be four times two.

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Should be eight.

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Right.

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And here is the result.

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That is cool.

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So we can do a more complex math functions here right now.

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Let's talk about module.

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Now, what is module?

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Well, module gives you the reminder.

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So let's write in the console.

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So for this, I'm going to show you in the console.

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Right, just to make just to make you practice that we can even use the condom.

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So 16 Modula.

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And seven, and that will give me to why?

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Well, seven can be contained two times.

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So two times, two times seven it will be 14 and 16, minus 14 is two.

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So Modula will give us the reminder, right.

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The reminder of 16.

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So how many times seven can be contained in 16 times and two times 17.

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So let's do this two time seven, not 17.

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It will be 14.

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So 14 minus 16.

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That will give us the reminder.

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So that is how we can use model right now.

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That is pretty much with numbers.

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Let's do the second JavaScript type and that will be string.

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Now, what are strings?

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So string is text in JavaScript needs to know if you are writing text.

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And for this we need to use single or double quotes.

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So that log and let's say I just want to print out my name.

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Rick.

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Good.

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Now use single quotes, but you can use double quotes.

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Let's see if it is Rick.

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Now what we can do, we can cancel out my last name.

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Let's use double quotes.

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It's not going to change anything.

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Make sure that when you use double quotes here, you need to use double quotes at the end.

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So save it.

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Here it is.

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Now we can do something more interesting.

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Let's do cancel the log.

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So strings are very interesting to you.

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So I'm going to say Rick here, plus Lewski, my last name.

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And so this here is not consider as a mathematical symbol.

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So this here is considered as concatenation.

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And what it will do, it will it will combine it will actually glue Rick in Sokolsky together so those

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the two strings will be attached one to each other.

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And this is not good.

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But what we can do, we can fix it.

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What are we can do space here that will fix it.

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Right.

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Or we can get.

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With space here, that will fix it, but sometimes you will see that some people are doing this.

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Should they making an empty string here, right, so it's a space between but again, they need to use

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the plus sign to concatenate with this one.

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So the empty string will be concatenated with the first part, right.

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This one.

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But also the empty strings need to be concatenated.

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Second part.

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So save that and it will yield the same result.

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Very good.

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But.

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So I used single quotes, but what if I want to do another quote inside?

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So, for example, I own something.

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So it's Rick's car, for example.

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Let's do it.

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Cancel that law and let's write Rick's.

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Like that, and it's not allow me a car, should I have it here, so let's change this to double quotes

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here.

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Nice.

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So this should work, but in the past it wasn't working because I use double quotes and single quotes

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together, but if I use single quotes, then I do have a real big problem.

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Now, why do we have a real big problem?

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Well, in JavaScript, we can use something that, Wolf, will ignore this quote.

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So the solution is to use backslash.

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So we use backslash here.

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And what we are basically saying to the compiler, OK, what's after the backslash consider is a normal

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stream so that now the S this one.

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Will be considered as normal, so riska, no more problems, right?

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So.

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By using the backslash, we can escape the quote and we can tell the compiler to ignore it and just

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want to use the tactic to be included.

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So that's why we use we need to use the backslash.

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OK, now, another awesome scenario here.

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I forgot the semicolon.

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Make sure that you write semicolons.

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It will work without semicolons, but it's always good at the end of the expression to write semicolons.

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OK, now let's consider one awesome scenario.

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What we think will happen if we try to combine numbers, something that we have done here and strings.

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So cancel that lot.

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Let's do it like this.

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So let's say thirty three plus years now save it and let's go back here and it's saying thirty three

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years, even if I put here space, still going to be thirty three years.

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Right.

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So why this is happening.

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Why this result.

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Well JavaScript will convert the number to a string.

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This number two, a string one, because the plus sign will tell the JavaScript compiler, OK, we have

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no in the string and the plus side probably means concatenation.

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And that's why it will glue this the same as we did here.

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Right.

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So that is pretty much it.

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So this plus sign doesn't mean mathematical operation in this because we don't have two numbers.

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And it say because we do have a string together with a number, let's do a concatenation.

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So it doesn't matter what you're going to put in, it's going to be considered as concatenation.

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That is pretty much it.

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Now, the thirty three it's not.

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00:17:38,150 --> 00:17:39,010
No, here it is.

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It's a different color.

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00:17:40,070 --> 00:17:47,210
It's converted back to a string, so it's automatically converts 33 to string because it's not addition.

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It's concatenation and that depends on the circumstances.

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Now what if we do another scenario?

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00:17:53,610 --> 00:17:54,280
Copy this.

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00:17:55,050 --> 00:17:59,770
Well let's put here thirty three minus just like this.

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00:18:00,410 --> 00:18:05,240
What if I have here a number in quotes that is considered as a string.

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00:18:05,240 --> 00:18:05,530
Right.

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Save it.

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00:18:06,320 --> 00:18:07,590
But let's see what will happen.

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Wow.

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Something strange.

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00:18:09,740 --> 00:18:11,420
Now I do have a blue twenty three.

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00:18:11,420 --> 00:18:14,490
That means it's a number in why this is happening.

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00:18:14,510 --> 00:18:18,590
Well we don't have anything for concatenation.

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00:18:18,590 --> 00:18:25,580
The plus sign can be used for mathematical operations like this, but also when we try to glue or attach

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the strings to each other.

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00:18:27,080 --> 00:18:29,320
But here with the minus there is a different story.

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The compiler will say, OK, whatever you have in the bracket, just consider it to be as a number because

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00:18:36,560 --> 00:18:42,680
we don't use no minus or this symbol here for concatenation.

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00:18:42,680 --> 00:18:45,350
And that's why it will convert this string to a number.

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00:18:45,620 --> 00:18:49,250
And yeah, we will have back and no result.

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Now, the last thing that I want to discuss today is.

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00:18:54,550 --> 00:19:05,140
William JavaScript, that's so boolean is also true or false, so Boolean is used by our computers.

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If you have done some EITE qualification, you will know that the entire computer code is written using

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00:19:12,850 --> 00:19:14,070
ones and zeros.

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So.