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The Solution
3:45See how to implement one possible solution this conditional statement challenge.
How did it go?
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If you didn't get it to work,
you can watch my solution
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compared to what you wrote and
then try to recreate it yourself.
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Also, keep in mind,
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there are usually many different ways
to solve a programming challenge.
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Your solution may be different than
mine and still work, that's fine.
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So the first thing that I'll do is I'll
move the declarations for the num2 and
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message variables to the top
of the math.js file.
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I'll also remove the var
keywords from down below.
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This practice session requires that
you use a conditional statement.
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But where should you put it?
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Let's look at the requirements again.
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I'm supposed to check the values of
the inputs, are they numbers or not?
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So I can put the conditional statement
right after I collect input from the user.
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So I start with the if clause,
followed by a condition in parentheses,
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and braces to mark the opening and
closing of the conditional.
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Anything I add in here will run
only if number 2 is equal to 0.
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I'll add an alert Message.
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Let's see how this works,
I'll save and preview the file.
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Type a number for the first input,
and 0 for the second.
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Excellent, here's the alert.
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Uh-oh, unfortunately,
it still prints to the page,
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that's because the rest of the program
is outside of the conditional statement.
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We need to add an else clause to stop
the programming from generating and
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writing this message.
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I'll add an else clause and
another set of brackets.
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Okay, I'll save the file and
preview again.
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Great, I get the alert message,
but nothing is printed to the doc,
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that's perfect.
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But I also want to check that
both inputs are numbers.
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I can add a branch to this
conditional statement.
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I'll do that using an else if clause.
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To check to see if
a variable holds a number,
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you can use the is not a number method.
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So I'll first check to see if
the num1 variable is a number.
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Inside these brackets, I'll add the alert
message that appears if the user types
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in text in the prompt dialogue.
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But we also need to
check the second number.
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One way you could do this is adding
another else if clause to test
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the second number.
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But that would be extra programming
that's just not necessary.
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Another way to do it is
add two pipe characters,
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followed by a second condition.
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The pipe characters
indicate that either one or
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the other of the test have to be true.
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In other words,
if either number one is not a number or
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number two is not a number,
we should alert the user.
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At this point, we have conditional
statements with three branches.
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The first two test for errors and
the last writes a message.
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Let's check it out.
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I'll leave the first input blank and
then type hello in the second, excellent.
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And when I reload it and
use numbers, it works.
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I hope you're able to complete
this practice successfully.
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If not, why not start over and
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try to write the program
without looking at my version.
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Have fun with JavaScript,
and see you again soon.
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