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Conditional Terminology
4:12We'll look at two "if..then" statements in this video to remind ourselves how they work. In the videos that follow, we'll see how to reform these statements into different conditional patterns.
[MUSIC]
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Hello there, Andrew here.
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JavaScript developer, lifelong learner,
and teacher here at Treehouse.
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I'd like to show you a few ways
to represent decisions in your
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JavaScript code.
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You've already learned how to write an if,
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else statement, to choose between
one scenario and another.
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This is called a conditional because it
does one thing if a condition is true and
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something else if it isn't.
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The paths that's an if, else statement
follows are called branches.
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They branch the flow of your programs
logic in different directions
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based on the results
of a conditional test.
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You can branch off in as
many directions as you want.
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Let's look at two examples of branching,
using if statements.
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A two way and a multi way conditional.
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We'll meet them in different ways later.
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First let's look at a very simple
example of if, else statements.
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If you'd like to follow along, open up the
workspace with this video or if you prefer
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to use your own text editor, download
the project files with this video.
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I have a file named two.js, which is
a simple example of two way branching.
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I have another file named multi.js,
with multi-way branching.
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And another file short_circuit.js,
with no code in right now.
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I'll run these in node but
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everything I'll show you in this
workshop will work in the browser too.
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In two.js, you see that I have a variable
named is true which is set to true.
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If the variable contains a true
value the console prints yes,
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if the value is false
the console prints no.
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Let's run this by typing node two.js and
we see that yes it's printed.
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Now if we change is true to false and
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we rerun it we see no.
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Let's take a look at multi.js now,
we have a multi-way branch here.
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If the day value is zero, then the
console prints the string Sunday.
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If it's one, Monday.
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Two, Tuesday.
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And so on.
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If it's not a number between zero and
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six invalid day will be
printed to the console.
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Let's see this in action.
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Day is set to 1 now.
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So when we type in node multi.js,
Monday appears.
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Let's change it to four and re-run it.
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We see Thursday.
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If we change it to new Date().getDay()
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you should see today's day.
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This may not be quite accurate
if you're using workspaces
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depending on the number of time zones
between you and Treehouse servers.
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If you run this locally on your computer
you should get the correct day there.
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Let's see our default case now.
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Set day to 8.
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And run the script.
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We see Invalid Day.
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Great.
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We'll come back to these examples
in the following videos and
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rewrite them with different
conditional statements.
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The conditional statements
we'll look at in this workshop
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aren't necessarily considered
best practices, but
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you will see these pop up in stack
overflow, tech blogs and other code bases.
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So it's good to know about
them understand them.
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Our first stop on this tour is
to visit the switch statement,
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a very compact way of adding multiple
branching logic to a program.
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I will see you there
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