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Welcome back to Section three, lesson five, declaration and assignment today we're going to be talking

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about variable declaration and assignment and how we use variables in JavaScript.

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Variable declaration is simply using varlet or const these special function keywords that we use to

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denote that we're initializing a variable and giving that variable a name.

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So in this situation, we would use either const Aulet or VAR and I can talk about the differences of

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those and then you just give your variable a name your variable cannot start with.

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Remember, it cannot start with a number.

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There are a few other rules, but for the most part you want to give your variable a name that is descriptive

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for what you're trying to accomplish.

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If you want the value of this to be something related to a car, car would be a very good name for your

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variable.

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If you wanted to have some number that you're probably going to change using some other code, then

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Count is a great name for that variable and you can make these whatever you want.

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Variable assignment is when you use the assignment operator, which is the equals sign to give the variable

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a value.

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So you're going to start with some value.

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Use the assignment operator and then your variable name, and that way they'll be tied together, variable

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assignment can be described either as putting this data into a box with this label or alternately thinking

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of the variable as a shortcut.

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Like on a computer, you can set a shortcut to open a file.

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The variable is a shortcut which is linked to this piece of data.

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So whenever you access the variable, it will access this piece of data in an algebraic way.

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So you can do them both separately or together, you could just do them by themselves where you declare

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and do the assignment later, or what typically has happened is you do both at the same time.

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So you would say the variable keyword denote the name of the variable.

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Use the assignment operator and then.

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Do the assignment.

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So let's go look at our code.

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OK, so let's show you an example of how we do this.

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Variable operation.

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We're going to start with declarations, so I'm just going to start with a let.

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And say, let me count equals zero.

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OK, so alternately, I could have started with just let count

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and then assign count equals zero.

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Let count, count equals zero.

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OK, so this is a declaration

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and this is an assignment.

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OK, if you want to do them at the same time, let's do a separate one.

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You could do a declaration and an assignment in the same stroke declaration and assignment.

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OK, the declaration comes from declaring the variable by stating the variable keyword and then the

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name of the variable.

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The assignment comes from using the assignment operator and giving it a value.

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So if I want, I can set that one to one.

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Now we have the difference between the two of them and I can access my variables.

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OK, so let's save that and see how this looks.

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Zero and one.

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OK, zoom in on our console so we can see that.

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All right, so that is declaration and assignment in JavaScript, and you can do the same thing, some

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other things you might need to understand is that you're going to run into some issues if you do this

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with CONSED.

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So if we say that just as is and give it a shot, there's a problem because cost is for constant variables

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and that means you cannot edit them after they have been declared.

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You need to initialize a const variable with a value.

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So you need to give this some kind of a value to start out with, and it's going to keep that same value.

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And you're not going to be able to edit that value because it's a concept.

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And the purpose of const is precisely that is to have a variable where you set the value once and then

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the code will not let you reset that value later, OK?

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But as you can see now, we can.

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Another thing you can note is that you cannot access count three before it's been initialized, so let's

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move the console lock down.

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Remember, you can hoist with far, but you cannot hoist with Consed, so one zero one and two.

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There you go.

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And we've got them.

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OK, and of course, you can do the same thing with Hvar.

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Now, the tricky the funny thing about far is that you could actually just declare a variable and reassign

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it.

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And this is by default, going to be a var, so it's the same as if you had the VA keyboard, so the

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default behavior for variables in JavaScript is VA and that's why we have to specify if it's a letter

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or a const.

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OK, so we save that refresh count for is not defined.

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So let's do that again.

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OK, let's see that.

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Let's get rid of that one.

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All right, so you can see where that's being defined.

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OK, so console log, count one, count two, count three and count four, in this case, this is a

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var.

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And so it'll behave the same exact way as we had before.

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That's being specified as a bar and if you don't specify anything, it's still a bar.

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OK, so that is our assignment for our lesson for declaration and assignment.

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Now we go on to lesson six.