In this movie, we're going to take a few minutes to talk about variables. Now variables is a concept that all programming languages have. A variable is simply a container to hold data. Now that data can change, it doesn't remain the same, but it's a way to store that data so you can use it later or use it multiple times. Now let me open up the JavaScript console. Now in an earlier exercise, we did the following.

Created a variable and set it equal to my name and then we did console dot log to display the variable to the console. And that's what it does. Now we could have just as easily done this The end results would be the same as you can see. So why use a variable instead of just entering the name? Well, the the advantage of the variable is that it really could contain any name. Let's just use an example that we have a website where we have the user enter their information, their profile information.

And depending on which user is on the website, that's the name that is going to display. It uses the same variable, but the contents of that variable variable just being a container, the contents of that variable would be different. Another reason is once it's assigned to a variable, we can use it over over over and over again. For example, there's one again, we just continue to use it and that's another advantage of a variable All right, let me clear my console. And let's talk about the syntax of a variable. We've seen it already.

But let me talk about the parts. var is an important part when you're declaring a variable. This is a reserved keyword in JavaScript, then the variable name. Then the assignment operator, which is the equal sign assignment operator, this is saying the value on the right of this is what's going to get assigned to the variable. Put my dog's name pika. That gets signed to the variable dog's name, and then we close it with a semicolon.

Once again, that semi colon is optional, but as I've recommended, you should always enter that we just created a variable. Now to reference that variable, we simply use the variable name There we referenced the variable. So anytime we use the variable name, it references it and then it pulls the value that was stored in that container out and does whatever we need to do with it. In this case it displays it to the console. Now another thing about variables is we can update an existing variable. So if I wanted to change the dog name to rollover, I would simply reference the variable, but the assignment operator and and then put the new value I don't use var again var is only use the first time you are declaring a variable.

So var is for declaration. Once you've declared a variable, you can change it and you change it without the var keyword. Now when I reference the dog name variable, it comes back as rover. Let me clear the console again. And let's create another variable we're gonna call this variable greet greeting. I can spell.

We're going to put in there the text. Hello there. Okay, we have that variable established. Now notice what we can do now we have two variables. We can concatenate them together. And it displays the contents of both of them.

So, an example where variables are valuable, let's say we have multiple Greetings, we want to get a particular user. Well, we just have multiple variables greeting, one, greeting two, greeting three could be named that way, or greeting formal. That's another way that you can use variables. This is something else we can do. I'm going to create, declare one more variable, full greeting. I'm going to set this equal to the contents of the other two variables we've created.

Now when we enter full greeting, it comes back Hello there rover. So it has the contents of those two variables in it. So that container now contains what was in, in the two other containers. All right, we can also do this with numbers. So let me clear again. Let's create a variable num, and set it equal to 32.

There we go, num is equal to 32. Let's create another variable num two is equal to five. Now we can manipulate the data in the variables the same way we did with the values in the previous in a previous movie. We use operators to do that. So num plus 10. Comes back 42 we can also do num And then some operator and the other variable.

So this is going to be num times num two. So the contents of num is 32. The contents of num two is five. And that comes out to be 160. Now if we change num, then do the same statement again. And then what I'm doing here to get back to a previous statement i'd enter as I'm as I'm pressing the up arrow, the up arrow in the console take you to statements you've already entered.

So I'm going back to that previous statement, I want to enter it again. Now this time we get a different, different result because num has changed. Num is no longer 32 num is now 10. So we put a different value into that variable. And we can do the same thing. With this variable.

We can create a new variable and set it equal to The product of the other two variables