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Hey, everyone, let's now solve the last of the exercises.

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So, number four, we should run a loop through this array and then we should print.

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Each of the sales inside this table and we should calculate the results, but we have to ignore the

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sales if a refund has been requested.

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So to get started, let's copy this.

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And let's bring it to visuals to record, so now this is.

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Number four.

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And now we have all this array.

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So let's start a loop, so let's use a for loop.

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So A is going to be actually, I don't need the VA keyword here, so A is going to be less than Salce.

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Not lenth.

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So now, in order to make this easier at every iteration of the loop, I'm just going to.

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Create a variable called sail, and I'm just going to assign sails.

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With an index of a.

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Because then in the first iteration of the loop, this is going to go to the sale variable, then this

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one, so now it is going to be easier because I won't have to use this notation every time.

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I would just use the sale variable.

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If you want, you can choose a different name because this may be a bit confusing.

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Sale and sales.

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You can use a different name if you want.

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For me, this is good.

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So let's see how that table works.

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When we go here, we can see that we have a row, so at the beginning of the loop we are going to start

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a row and then we just need to send three T.

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D elements with the name, date and amount.

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So at each iteration, we are going to start a line and age HTML line.

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Which is going to start by opening a table row, then we are going to add.

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The tea, the elements, so we are going to add a TD.

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So here we just concatenate it.

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So now we have.

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The table and inside it, we are going to concatenate something so TRD plus the name of the student,

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so the name is going to be Sayle, that student.

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So this is why I created this variable first, just so I don't have to repeat this all the time.

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So Sailboard student.

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Then I'm just going to close this.

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Now, I'm just going to do the same thing for the date.

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And for the amount.

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Let's remember that the amount is a number and we are concatenating this with text, so in order not

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to do the same mistakes we did before, let's use the two string method.

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Now, this is better, and here it's I think this error is because we are using the VA key word, so

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let's try to erase this.

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So now this is correct.

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Now we are just sending the three informations we need.

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And now we are just going to finish our line.

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By closing the table wrote.

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So closing the table wrote, OK, so when we finished doing this.

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We can just get that element.

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Which is going to be, let's see, the stable, so the tea body.

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Is where this is going to be.

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So the idea is course sales.

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So the inner age TML.

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It's going to be plus equal line, so we are concatenating otherwise at every iteration of the loop,

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we would just erase what's inside you.

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So this is why we need to concatenate or increment the value of this inner HTML.

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Pretty cool.

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Now, we know that before starting the loop, we can just clean what's inside here.

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So we've done it a few times and we know why we should do this just to erase this line that I left here.

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So before we move ahead, let's see if this is working.

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We still need to ignore if there has been a refund.

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But for now, let's just test if this is working.

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So we should always do stuff step by step.

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So refreshing saving this and refreshing the page.

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Going down here, we can see that we were able to do the first part, so we are sending these values

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to the table, which is pretty cool.

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Now, there was a refund.

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So here Martin Hayse and Martin is here, so we should not use it.

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So now let's fix this.

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So now we can just use an if statement.

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And this time we can actually we should create the sale variable before we do this test, because now

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we are going to test if there is a sale that.

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Refund requested.

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If there's no refund, this is going to return no, and we know that JavaScript considers null to be

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false.

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So in this case, we are not going to enter here.

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So now how do we write it in a way that we don't need to do it like this and just leave it blank here

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and just paste all our code inside the else statement like this?

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Because if there has been a refund, then we shouldn't do anything.

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Because we are not going to use it in the calculation, we are not going to send it to the table, but

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if not, then we are going to run all this.

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But this is a bad way of writing and we don't need our statement.

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All we need is.

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Test the opposite.

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So how do we test the opposite?

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We use the exclamation mark.

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So like I said, this means not so.

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I didn't show an example like this before.

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So if you want, you can just do sale that refund requested.

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Equals, no, you can do it like this, but it's much better to do like this because then we are just

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testing the opposite of what we wanted.

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So if this does not return false.

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Then we're going to do all this, let's see if this is working.

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Refresh the page.

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And now we don't have Martin Hayes in the list anymore, pretty good, so now we just have to calculate

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the total.

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So before starting the loop, let's start a variable for the total sales.

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That's going to start as zero.

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And then at each iteration of the loop.

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We are just going to do total sales plus equal.

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Sale, that amount.

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We already have it as a number, so we don't need to do any conversions, and now this time we should

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only print it when we finish the loop, we don't have to replace that value every time.

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So when we are finished with the loop, so when we run through all the sales we have, we can just send

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the result to that element.

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So let's go there.

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Let's click here.

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We can see that this TRD element has its own ID.

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So this is what we need.

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And now we can send the total sales to this element.

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So let's save this, let's refresh the page.

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And now we can see that we are starting to do interesting stuff, if you had problems solving this one

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because of the table, I expected you to have some knowledge of age HTML.

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But if not, don't worry.

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Sometimes students, they they get a bit frustrated because they cannot solve an exercise.

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So they they tell me that I did not teach something before sending the exercise.

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Well, don't worry too much about this because this video with the solution for this exercise is also

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a lesson.

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So if you had trouble with this, that's not a problem.

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The important is that you see the solution, then you see how to do it.

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And now what you can do is just erase all the code and try to redo it this time by yourself.

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And then you are going to learn how to do this.

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And about the exclamation mark that I've used here, again, you don't have to use it if you don't want,

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you can just do it like this if that refund requested.

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Equals No.

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As you can see.

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This is going to work the same way, so again, I just wanted to show you something different.

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If you want, you can research more about that operator.

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So I hope you like this exercise.

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Now, we are starting to do more complex stuff and we still have a few things to learn about JavaScript.

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So I'll see you in the next video.