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Hey, everyone, let's get started with exercise number two, so the Jason below represents a list of

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courses.

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Each course has a title and an array of reviews create a function to pass the Jason, add another property

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for the average rating of each course, then return a new JSON with the updated object.

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So we also have some additional rules down here.

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But let's get started with the first part of the exercise.

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So let's just copy this.

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Let's pretend we just received this data from an external source like an API.

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So going back to Visual Studio Code, let's base this.

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We have some RAD underlines here, which indicates errors.

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But this is just because we broke lines.

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We can just move everything into a single line like this.

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And now we are good.

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All right, so let's create our function, so I'm just going to create a new function here called maybe

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average.

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Reviews or something like this?

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Now we need to pass an argument which is going to be our Jason, so for this, since we are simulating

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a request to an API, I'm just going to call it data.

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So the data that we are going to pass as an argument is just going to be this, Jason, that we have

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right here.

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So the first thing we're going to do when we start dysfunction is creating a variable.

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I'm going to call it causes.

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And we shouldn't worry about any conflict between these two because this variable here is inside the

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local scope of this function.

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So this is completely fine.

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So, of course, this is going to be Jason.

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That pass.

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And then we are going to pass the data.

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So if we do this, we should have our data as a JavaScript object.

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So let's do a consult that clock just to see if everything's working, so let's send the courses, which

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again, it's not going to be this one, but this one inside the local scope of the function.

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And we also need to execute the function on page load.

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So right here we are just creating this function, we still need to execute it, so let's do it right

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here.

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And as an argument for this function, we are just going to pass the courses variable, which is the

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one in the global scope.

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So this one, it is going to be passed as an argument of this function.

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So everything should work if we do like this.

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Let's save this.

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Let's go back to our page.

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I'm going to refresh the page.

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If I go to the inspector, let's go to the consul, and now we are seeing an array.

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So every element of this array is a course which has title and reviews.

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So, again, title reviews.

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Pretty cool, so we're getting somewhere here.

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All right, so now we need to add the average rating for each of the courses, but we have the second

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part of the exercise, which is using the tri catch intro to comply with the following rules.

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So if the course doesn't have any reviews, so instead of showing zero, we need to show no reviews.

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So then we are not going to show a number, but we are going to show a string that says no reviews if

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the course has less than five reviews.

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So from one to five reviews, we should show not enough reviews yet.

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So we are still not going to show the average.

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Otherwise the property should receive the average rating of the course rounded to one decimal place.

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So this should be pretty simple to do.

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So let's go back to Visual Studio Code.

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Now that we know that we have an object, we need to iterate over this array of courses.

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So let's start a loop.

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So for.

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Let's use a this is inside the scope of this function, so that's OK to use a we don't have to use that

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here.

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A is going to be less than horses.

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Not lenth.

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And a plus plus, that's the basic structure of a loop.

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All right, so when we are inside this loop, the first thing we are going to do is create a variable

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just for the reviews so we can work with it.

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So reviews.

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Is going to be coarsest.

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With an index of a.

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Then.

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We need to get this property, which is called reviews.

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Now we need to use a tri catch statement here, so let's use the tri.

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Then after it comes the catch.

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We need to pass an argument here for the error.

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Panel, what we're going to do here, first, we need to create our own errors, so let's go back to

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the page.

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And here we have two situations that we need to create in the code.

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So the first one is if the course doesn't have any reviews.

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So how do we do this?

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We just start an if statement, so we just created a variable for the reviews.

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And if we go back here, let's see this one.

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So this one has eight reviews, so it's an array with a length.

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This one is just an empty array.

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So we can just test if this array has any elements inside.

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So for this, we're just going to do if.

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Reviews.

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Not.

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Lenth.

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Is zero.

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Then here we are going to throw our custom error.

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So we're just going to throw.

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Let's go back there to see the exact message, so no reviews.

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That's the custom error that we need to throw.

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So here.

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We just started.

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Else if.

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And now the second rule.

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Is the chorus has less than five reviews.

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So here, if reviews start lenth, let's just copy this.

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It's less than five.

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Then we are going to throw a different error.

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Which in this case is going to be not enough reviews yet.

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So if this doesn't happen.

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It means that we have enough reviews, it's not zero, it's not less than five, so then we can start

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calculating the average reviews.

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So in order to do this, we're going to create a variable called some.

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Reviews.

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Because we need to sum all the reviews.

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And then divide it by the number of reviews so we can get the average.

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So the sum is going to start at zero and now we need to start another loop to loop through each of the

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reviews.

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So if we go back here, let's see this second course as an example.

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So we have.

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Eight reviews here from zero to seven, so we need to iterate through this array to sum all the reviews

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so then we can get the average.

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So let's just copy this structure here.

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Instead of a here, we need to use B, otherwise this is going to conflict.

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Because both are inside this for loop and inside the function.

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So here we need to change the name of the variable.

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All right, so now we have B.

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And it's not courses, not length, but reviews that length.

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So some reviews.

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It's just going to be.

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Its own value plus.

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Actually, here is not courses that reviews.

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But just reviews.

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Because that's the variable we just created.

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So now it's good, so reviews with an index of the.

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So by doing this, we just have the sum of all the reviews from this course and now.

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Let's create another variable called average.

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Reviews.

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Which is going to be the sum of reviews.

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Divided by.

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Reviews that lenth.

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All right, so what do we need to do with it?

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Let's remember that we are inside this loop iterating through each of the courses.

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So what we need to do is just adding a new property to this course.

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So let's do this here.

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So this course, let's create.

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A new property called.

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Average rating or something like this.

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And then we are just going to do this.

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But this has to be rounded to one decimal place so we can just use the two fixed method.

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And here we just want one decimal place, so if we reach this point, we are going to add a new property

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to this object, which is going to be the average rating.

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If we have any problems inside this try block, so it means that we.

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Reach these throw statements, then we need to do something else here.

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So it's going to be similar, but we just need to save those messages for the errors.

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So we can just add the.

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Error argument, which we know that by using the throe.

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Statement, I'm just going to send this to this argument.

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So after we do all this, so now we finish this for loop, we should have everything we need before

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we transform this back into a Jason.

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Let's send it to the council so we can see so here we have this crisis variable that we created.

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All right, let's save this before we refresh the page.

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Just one thing I just realized.

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I'm missing a dot lenth here.

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So B should be last than reviews that length, this would probably cause an error.

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So now I think it should be good.

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Let me save this.

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Now, refreshing the page now if we go inside each of the courses, so let's see the page, because

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we can see that now not only we have the title and reviews, but we also have a new property called

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average rating.

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So in this case, we have no reviews for this course.

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So we have just a string here that says no reviews, which is correct.

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Let's close this one.

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Let's go to the next.

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Now, we have this course with eight reviews and we can see the average rating of four point eight.

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So this is rounded to one decimal place, which is good.

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Let's go to the next one.

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So here we have the Python course with 10 reviews, average rating, four point four.

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Pretty good.

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Let's see the last one.

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So now machine learning, we have only three reviews.

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So the tax here is not enough reviews yet.

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So this is what we had to do with exercise number two.

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Actually, we are not finished yet just because we need to return a Jason, so that's the only thing

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we need to do to finish.

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So instead of doing this, let's just return the courses.

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But actually, we are going to use Jason, that string ifI.

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And then we can do like this, so our function is just going to return a Jason.

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Back so here.

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If we want to see it in the can so we can do anything we want with this function because it's just returning

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a JSON, but if we want to send it to the council, then we can just do it like this just so we can

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see it.

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So now we are sending the result of this function to the council, which is this, Jason, that it's

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returning, let's save this.

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Refreshing the page, and now we are adding a property.

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To our object, following the rules, turning it back into a Jason and returning it, so that was exercise

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number two.

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If you have any questions, you can just leave it in the Q&A section, if not, just go to the next

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video so we solve exercise number three.

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I'll see you then.