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All right, so continuing with our exercise, we just have one left, so let's check it out, see the

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shopping list below.

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So before reading the rest, I'm just going to copy this and paste it inside the code.

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So this is number four.

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And now we have the shopping list, so now let's go back there to see what we need to do, so do the

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following changes to the list, get the last item and place it at the beginning of the list.

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Then we just need to add two more items at the end of the list and show the updated list.

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Let's just copy this.

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Take it to the code just so we can see it.

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So now we just need to get the last element of the list and place it at the beginning, but I cannot

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count how many elements I have and just use a manual index because the code that we write must work

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with any list.

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So if we have a list of three elements, the same code is going to work.

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If we have a list of 30 elements, the same code is going to work.

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So how do we get the last element dynamically?

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Well, to get the last element of any array, there's a trick we can do that uses the length of the

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array, so.

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Let's just create a variable called last.

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Element.

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And now we're going to get this array.

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And we need to pass something as the index, so any time you need to get the last element, you can

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just use the length of the array.

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I'm going to explain this in a moment.

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So as an index, we're going to use the length of the array.

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And then we can just subtract one, how does this work?

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So let's forget this.

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Let's create.

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Another array with only two aliment, so we can see how does this work?

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So here we have two elements and what are the indexes of those elements?

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So this one is index zero and this one is index one, right?

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If we do length of this array, what's the number that we are going to get, we are going to get to

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because it has to element.

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So this means that the last element of an array is always its length, minus one.

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So its length is two.

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Minus one is exactly the index of the last element.

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So by doing this, it doesn't matter if we have an array of 30 elements, three hundred elements, three

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element, it is always going to get the last element.

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So by doing this, we already saved the last element.

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And now we can just do.

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Shopping list.

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That pop.

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We know that this is going to remove the last element, and now we already have it.

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And then we can do shopping list dot.

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On shift, which is the method to add elements to the beginning of an array.

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So then we can just use this element that we got before we removed it.

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So now before moving ahead, let's just do consult that log.

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With the shopping list, just to see if we were able to get chocolate and place it at the beginning

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of the array.

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Refreshing the page now we can see the chocolate is now the first item.

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And like I said, it's important to do it the way we did now, because now it doesn't matter the size

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of our array, this operation that we just created is always going to work.

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All right.

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So now let's move on to the next add two more items at the end of the list.

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So this should be pretty simple to do.

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We can just use shopping list.

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That Bush.

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Which is the method to add these elements to the end.

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We just need to do this separately because these need to be.

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Separate elements, we don't want cheese and eggs together, so cheese.

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Eggs.

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Going back there, refreshing the page, now we can see that we moved chocolate to the beginning and

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we added cheese and eggs to the end of the array.

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So now we are done with this exercise before I finish this video, I just want to show you something

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interesting.

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There's an easier way to do this chocolate operation that we did.

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Let's just make one test here.

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So we have this variable called shopping list.

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We can access it from the console.

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As we can see, we have 10 elements.

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And what happens when we use the.

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Method, so I'm just going to do pop.

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I'm going to press enter.

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And as you can see.

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This method not only removes the element, but it also returns something, so it's returning eggs to

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us.

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So this means that we don't need to get the length of this array and do all we did just to get the last

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element, because this method not only is going to remove this element, it is also going to return

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it.

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So going back to our code or let's try it here first if we do a shopping list.

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Then we use the on shift method.

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To add elements to the beginning of this array.

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What we can do is just getting this pop.

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Method.

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So when we executed inside here, not only it's going to remove the last element, but it is always

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going to return which element was removed.

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So then we can use this element in the on shift method.

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So now we just remove removed eggs.

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Before doing this, let's check the array again.

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So now this is how the shopping list looks like the last element is cheese, so if we execute this.

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First, it is going to remove the cheese, then it is going to return the item that has been removed.

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So it is going to replace.

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She's here.

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So by doing this, we are able to add it to the beginning of the array.

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Let's see if this works.

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Let's just press enter.

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Now, let's check the shopping list.

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And we can see that we just did the same thing with less lines of code, so let's go back there and

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let's add this different solution.

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So here we have the solution for the Shacklett, which used three lines of code.

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I'm just going to comment this shift at a.

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And now the only thing we need to do here.

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It's just using the UN shift.

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And here we can just use shopping lists, dot, pop, because this not only is going to remove chocolate,

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is also going to return what has been removed and by returning it, we can use it inside the unshaved

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method.

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So saving this.

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Refreshing the page, we can see that we have the same result.

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So I hope does not overcomplicate thanks to you.

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I just wanted to show you this, because when we are writing code, we should always try to be efficient,

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which means using less lines of code to get to the same result.

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So that was it for this exercise.

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In the next video, we are going to start diving deeper into JavaScript.

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I'll see you then.