In this final practice with basic JavaScript objects,

I asked you to create an array of objects.

So let's start by creating an array, let products = [ ].

I'm using the newer syntax to create the variable, let instead of var.

Var works just as well, but check out the teacher's notes if you want to understand

the difference between the two.

Remember, use square brackets to create an array, and

use curly braces to create an object.

Now I'm gonna add an item to this array.

Because an object is a value just like a string, number, or boolean,

you can add object literals to an array to create an array of objects.

Just add an object inside the square brackets like this.

Start with curly braces, and then the key name and the value chair.

Inventory 5, and the unit_price 45.99.

So we've added one product, a chair.

There are 5 in stock and it costs 45.99 each.

To add another item to an array, just type a comma, followed by another value.

I'll add two more objects here.

The name will be table, inventory ten and a unit price of 123.75.

The last product is a sofa.

There’s two in stock and the unit price is 399.50, okay.

We have our array in place with three different objects or three products in it.

Now that we have an array of objects,

let's create some functions to work with that array.

First, a function that returns a list of the names of all of the products called

function listProducts has one parameter, prods.

That's the array of products that gets passed into this function.

Because the function returns a list of product names,

I'll start by creating an empty array to store that list in,

let product_names = [].

It's empty now, but we'll add product names as part of this function.

Next, I need to loop through the array of products, looking at each object and

retrieving the name of each product.

There are many ways to loop through an array in JavaScript.

I'll use a basic for loop.

Type for let i=0, i less than prods.length, i+=1.

This creates a counter variable, let i=0 creates a counter variable,

each time through the loop it compares the value of i

to the link of the passed in array of objects.

And exits as soon as that as equal to the number of items in the array.

In other words, it runs the code inside the loop the same number or

times there are array items.

In this example, I've got three objects, so the loop will run three times.

To access the name property of each object,

we first need to access that object using array notation.

So prods, bracket i,

closed bracket, accesses the array item that's at the i index.

In other words, the first item in the array.

In this case, it's the chair object.

The second product is at index 1.

And the last product is at index 2.

As the loop runs, the value of i increases.

Now to access the name properly, just add the dot syntax and

the property you want to access, in this case name.

I'm building an array of product names.

So I can use the array push method to push the name onto

the end of the product names array.

To do that, I'll start by typing product_names.push and

pass to the push method the name of that product.

Finally, I'll just return that array.

Return product_names.

Let's see if this works, by calling the function and

logging the result to the console.

I'll type console.log( ListProducts(products); So

I'll call up a loose products function and pass the products array to it, all right.

I'll save this file.

Open the console.

And type node 3_final_products.js.

And there's a list of all our products.

Excellent. We have one last function to create.

The total value function will calculate the total value of all the items in our

inventory.

It takes as an argument an array of objects.

So I'll type function totalvalue(prods) {}.

This is the basic structure of our function.

We'll calculate the value and return it.

So I'll create a variable to hold the calculations, and

then we'll use a loop just like we did in the previous function.

So I'll take let inventory_value = 0.

That's the starting value.

Then I'll do a for (let i=0; i-prods.length; i+=1), and braces.

Each time through the loop,

we'll add to the inventory_value variable by multiplying the total number of

the current product in stock by unit price of that product.

So, say we have five hats stocked and each hat cost 10.

The total inventory value of that product is 50.

So, I'll take the inventory underscore value,

I'll add to it prods i inventory times prods i unit price.

We loop through the array making that same calculation for each product and

adding it to the inventory value variable.

Finally, we just returned that variable, return inventory_value.

To finish off this project let's log the results of calling that function.

I'll type console.log(, and then call totalValue,

passing products as an argument.

I'll save the file.

Open the console.

Type node 3_final_products.js.

And there we have it, chair, table, sofa, and the total value is $2,266.45.

If your project isn't working,

check your code against the code pasted into the teachers net.

Pay close attention to the items you may have missed.

Think about why you might have missed them.

And if you need to, revisit the videos from the loops arrays, an object's course

that can help clarify what you're not quite yet understanding about objects.

Also, if you're stuck, it's often really helpful to reach out to our community and

post a question to the forum.

We have lots of students who are eager to help.

I hope you had fun with this practice session and

fun working with JavaScript objects.