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I know we spent quite a bit of time on variables, and this is going to be the last lesson to wrap up

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some more information about variables and data types, because they are so super important as the fundamental

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core building block when you are programming, so when you are creating a variable.

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So as mentioned in the last lesson, when you first initialize it, it's initialized as undefined.

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And when you declare a value, declare a variable to it, then that doesn't necessarily mean that you're

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signing a value so you can do it independently or you can do it at the same time.

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So by default, it's undefined data type.

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And you can see that when you just declare the variable, such as test and output in the console's.

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We saw a little bit of that in the previous lesson as well.

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You can also declare multiple variables in one statement.

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So all we have to do is comma, separate them and these are all going to come out as undefined.

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So here we've got an example, really simple example.

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So we've got VAR A, B, C, D, or you could use left or const, but of course, const wouldn't make

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a whole lot of sense because then you're just declaring a bunch of variables that are supposed to stay

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as undefined.

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So not great use of cost.

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So more than likely you're either using VAR or left, and if you're programming with the six then you

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are more than likely using left for that one.

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Also the naming conventions so you don't have to use it as Camil case, but as you can see in this example,

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user first names.

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So when we do create variable names, we try to make them meaningful for what contents we're expecting

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to hold in them.

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And it makes it a whole lot easier to read your code down the line and also remember what all of these

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variables are doing and what information they're meant to be holding and the way that we do that because

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we can't include spaces in the variable name.

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Otherwise, you're going to throw an error the way that programmers will do this and they write multiple

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words and they patch them together using cavalcades.

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So the first word would just be lowercase and then the second word would be capitalized.

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So here we've got user and then first name.

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So first is capitalized and name is capitalized.

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Sometimes you might see first name all as just F capitalized.

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So all depending on the style.

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And this is the preferred way to name variables so that it's easier to read.

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And this is again from programming perspective when you are accessing your code and you've got a whole

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bunch of code and a whole bunch of lines of code, you're going to be really glad that you named them.

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Well, there's also when you are naming variables, you can use underscore you could use dollar signs

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and you could use letters and digits.

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The only thing is that they can't start with digits.

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They have to start with either one of these to underscore the dollar sign or a letter so it can't start

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with a digit.

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They can be upper and lower case, no spaces and it is case sensitive.

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So if you got a variable with all uppercase, it's going to be a different variable than with all lowercase.

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There's also no limit to the length of the variable name.

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But of course you want to keep it manageable and you don't want it having to be too long because variables,

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typically you're typing them quite often in the code.

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And trust me, you don't want to make them too long.

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There's also some reserved words.

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There's not a whole lot, but there are some reserved words.

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And this is available at the Mozilla Developer Network.

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So JavaScript reference lexical grammar.

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So these are the reserved words.

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So you can't call your variable const const or let let doesn't make a whole lot of sense and you've

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got to avoid these words and everything else is OK.

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There's also a future reserved words that you got to be mindful of.

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So when you are naming your variables, do take a quick glance at this and just to keep it in the back

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of your head that when you are naming your variables, that you don't name them as observed word.

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And if you do by mistake, then you're going to throw an error on that one.

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So the challenge for this lesson is to create some variables, update the values and output them into

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the console, and also use the code block for checking to see if a variable is true and output a message,

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a secret message into the console.

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And then you can change that to false and see if you get a different output.

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So very similar to what we did in the last lesson.

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But it is meant to get you to practice and get comfortable with variables and this time focus more on

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what the names of these variables are as they relate to the content that you're holding within them.

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And then also try the Campbell case so that you have different variables that might have longer names

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to them.

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So go ahead and pause the video and I'll show you the solution coming up.

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And here's a quick peek at the code snippet that we're going to be working with.

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So the first thing that we're going to do is declare a variable and we're going to assign a value of

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two to it.

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So this is going to be a concert that we're going to be using and then also declare a variable.

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So message.

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And here we can have a welcome message to the website and then also declaring a variable.

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But we're not going to have any content in it.

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And we're use Kemakeza in order to name that variable and we can cancel out the value of more stuff.

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So let's see what happens.

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And there's also another thing that you could do within the console.

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So if you do have variables, you can just simply type them into the console and you can see that instead

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of undefined, the response back from the browser is going to be the value that's being held within

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the variable.

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So, again, this is super useful when you are debugging your applications and you maybe want to know

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what a variable value is at a certain time, you can console log it out or you can go into the console

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and type the variable.

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So next, let's check to see if test is true.

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And if it is, then we're going to do something else so we can console, like the value of message and

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then also update more stuff.

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So we've got a bunch of stuff happening in here.

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So this can be whatever values you want to set.

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And then also we're going to set value of in block and this is secret within the block.

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So no, not much of a secret message, but you can use your creativity and your imagination to come

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up with something even more interesting than that.

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And of course, I'm sure you can and then just console that out.

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So let's try that out so we see that.

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Welcome to the website.

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This is the secret within the block.

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Yes.

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Content is here.

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So let's toggle this and let's switch this to force and refresh again.

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And you see that all we getting output is undefined because, of course, test isn't running because

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this is false.

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And all of this information is just within this block of code.

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So try to have some fun with the experiment.

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And coming up next, we're going to look at how to create interaction.

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So using the prompt where we can get information coming from the user and that's going to start with

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our user interaction and JavaScript.