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Having a good understanding of what a
function argument means,

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we can now talk about another important
component known as default arguments.

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Sometimes, if an argument is not passed
through, but

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you want the function to have a starting
value no matter what,

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this is where a default argument will come
to your assistance.

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Now you can see it's just hello, dollar
sign, name.

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Then, we'll simply add name equals and

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then whatever our definition for the
default argument should be.

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In this case we'll just do friend that way
I can pass through an argument like this.

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So I'll say hello and then Mike.

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That way it'll say Hi, Mike, how's it
going?

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But if I choose to just pass through
hello,

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remember we didn't define anything outside
of the function scope like before, but

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now it's gonna say Hi, friend, how's it
going?

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Now what if we wanted to do multiple
default arguments,

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just like in our greet function?

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We'll simply add the same way we did it
before, which is equals friend and

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then equals morning on time_of_day and
name, respectively.

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This way I can still call, greet Mike
afternoon and

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get, Hi, Mike, good afternoon.

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But if I pass with no arguments
whatsoever, it'll just say, Hi, friend,

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good morning.

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Now let's say we wanted to make an
argument predefined as optional.

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Well the way we do that is in the same way
we've done default arguments.

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Let's say for instance, I don't really
need you to provide me a time of day.

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Well, let's do that by simply eliminating
it set to morning and

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make it equal to Null.

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This way, we have to check inside the
function if time of day is set.

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So we'll check if time_of_day, and

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then we'll surround our previous statement
with an if and an else.

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Now, if time_of_day is equal something
other than null,

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it'll say hi name and then good
time_of_day.

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But we need to provide an else as well.

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So what we'll do is just say echo hello
comma name.

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And close that statement with a semicolon.

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This way I can still say greet Mike
afternoon and get, Hi, Mike,

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good afternoon.

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But I'm also able to just pass through
Mike to our

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greet function without the time of day and
we'll end up getting this back.

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Hi, Mike.

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So now let's talk a look here in
Workspaces on how to

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work with default arguments.

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So far we have had some arguments here,
we've passed through arguments,

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if we don't pass an argument we'll end up
getting an error.

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So what we'll need to do is create default
arguments so

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that way we don't get the errors when we
forget to pass through.

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We'll also look at how to make arguments
optional.

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So, let's start with creating a function
that will show a little

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bit of info about someone and maybe who
they are or a title.

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So let's start with creating that
function.

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So function and then get info.

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'Kay.
And we're gonna have two argument here,

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one is gonna be the name and next one is
going to be the title.

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'Kay?

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Then open and close our curly braces.

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So now we have our function.

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Now inside of this function what we want
to do is just echo a string.

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So echo, and then we'll go ahead and

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do double quotes even though we're going
to output some variable information.

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So let's start with name and then has
arrived,

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they are with us as a and then title.

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So this way in a string format if I was to
say get info.

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And then pass through two strings.

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So let's say Mike and Mike is a frog.

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Okay.
So we have multiple arguments here and

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we have one is the name and next will be
in the title.

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So notice they are in the same order as
they were defined on line three.

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So I'm going to go ahead and save this and
then take out, take a look at the preview.

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So here we see it says Mike has arrived.

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They are with us as a frog.

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Okay.
That seems perfectly reasonable.

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Let's go back over and say that we forget
to type in frog.

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We just save this and hit refresh.

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It'll say Mike has arrived.

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They are with us as a, nothing.

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There's a blank.

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Well we don't want that so

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we're gonna need to define some kind of
default argument here.

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So let's go back over to our code and then
say, get info, title, and name.

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Well let's say we want to define a title
to start with so

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we say title equals, and this is where our
default is.

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And we'll say, friend.

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All right, now save it.

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And if we don't use title as an argument
it should come through as friend.

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So we'll go ahead and hit our Preview.

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Refresh.

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And there it says, Mike has arrived, they
with us as a friend.

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Which is great.

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Okay.

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Now what if we wanted to take, and make
the title completely optional?

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Well, that's pretty easy to do.

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All we need to do is remove equals friend,
and just simply say equals null.

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Okay, this way it's not gonna report back
any kind of errors or notices for us.

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But we need to do something a little
different.

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Cuz otherwise, it's just gonna come up
with that blank again.

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So let's create an if statement to test
whether or not title exists.

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So we'll say if, and then we'll say title.

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We don't need to see if it's true or
anything like that.

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Just simply saying if title, make sure
that it exists.

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It's anything other than null.

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All right.
So if title.

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We're gonna open and close our curly
braces, oh and then else.

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We're going to do something different.

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All right.

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Well I'm actually going to actually use
this line.

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So, I'm gonna cut it, and then head back
up here and paste it in.

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Make sure my tabs are good.

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Okay.

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And then here if we don't have a title, we
want to echo something different.

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So, echo and then name has arrived, and
then welcome.

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Perfect, all right.

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So now we close that with a semicolon to
end our statement.

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So if we go down and

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run what we have currently by going to our
preview button and refreshing it.

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Now it says, Mike has arrived, welcome.

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Because on line 13 here we did not pass
through an argument.

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But if we do pass through an argument here
such as let's say, frog.

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Save it.

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And then refresh our preview.

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Now it will say, Mike has arrived, they
are with us as a frog.

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So, in order to get a optional argument we
can simply

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pass through the default argument as null,
or we can pass through a string or

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any kind of value we want to use as our
default argument

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in the argument definition of the function
such as in line three.