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If a product is in stock,
let's also display its index or

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position in the product list.

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You learned that the index of method
returns the index of an array element.

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I'll insert it into the if
statement's message

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with it's dollar sign curly
braces inStock.indexOf search,

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then outside the curly
braces type on the list.

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I'll also display a hash symbol or
a number sign just before the index value.

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This is going to search the array for
the inStock product and

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return its index starting from 0.

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Now, if the user types pizza, for
example, they'll see the message,

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Yes, we have pizza, it's #0 on the list,
which seems a bit strange.

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Remember that the index of
the elements begins with 0.

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So I'll update this expression to
display the element's current index + 1.

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That way the products displayed to
the users starting from 1 instead of 0.

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Typing pizza into the prompt
dialog now returns, Yes,

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we have pizza, it's number 1 on the list!

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I'll try limes and see that limes are in
stock, and it's number 15 on the list.

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How about chips?

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Nope, that's not in stock.

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All right, everything's working so far.

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And notice how I'm writing a little bit
of code, then testing to see if it works.

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It's good to get into the habit
of programming this way too.

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This let's you quickly catch and
fix errors.

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Next, if the user clicks the prompt
dialogue's cancel button,

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that's going to return the value null,
which as you've learned,

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is JavaScript's way of saying
there's an empty value here.

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In this case,
the search variable points to nothing.

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Also if a user submits a blank search,
that returns the message, Sorry,

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we do not have, then a blank space.

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So I'll also check for any null or
empty string values using a conditional.

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I'll check for those values first.

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So I'll change my current if
statement to an else if clause.

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Then right above, add an if statement

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I'll use the logical not operator
in the condition to check if

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the value assigned to
the search variable is falsy.

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In other words, a value that's
considered false when evaluated.

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Examples of falsy values are null,
an empty string, the number 0, the keyword

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false, and a few others you can review
in the teacher's notes with this video.

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I'm only checking for
null and an empty string.

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In that case,
I want to list all the products in stock.

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I'll use a template literal to assign
the message variable a string holding all

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the products in stock.

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You'll learn that an array's join method
lets you create a single string composed

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of all the elements in an array.

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I'll call join on the inStock array.

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And to separate each element in the list,

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I'll pass the join method a string
consisting of a comma and a space.

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Now, when this code runs,
the join method will, for example,

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return a string like pizza comma space
cookies comma space eggs and so on.

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I'll test this by saving my file,
refreshing the browser,

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then clicking the Cancel button, and

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good, that displays all the products or
elements in the in stock array.

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They also appear if I
submit a blank search.

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Finally, the includes and
indexOf methods are case sensitive.

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Currently, all the in stock
array values are lowercase.

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So if a user typed an in stock item using
a capital letter or any uppercase letter,

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includes would return false,
and indexOf would return -1.

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To prevent that, I'll convert
the text entered by the user to all

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lowercase characters using
the string.2 lowercase method.

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This way if the user types pizza in all
uppercase, or eggs with a capital E,

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for example, this else if
condition still evaluates to true,

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and inStock.indexOf returns
the index of the element.

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There's another way you
might write this too.

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You can review it in the teachers
notes with this video.

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All right, up next, you'll learn
about more complex types of arrays.