Node.js Tutorial for Beginners - 8 - Modules Video Lecture | The Complete NodeJS Developer Course - Back-End Programming

all righty guys welcome back and in this
video what I want to do is I want to
start talking to you about something
called modules so eventually whenever
you rate an actual piece of software an
actual web app it's going to be pretty
long either hundreds of lines of code or
maybe even thousands of lines of code so
obviously as you guys could probably
already figure out if you just started
typing all that code in all of it was in
the same file then first of all this
file is going to get really cluttered
really messy you're really difficult to
work with so what we can do instead is
we can actually take that code and break
it up into different files
now in nodejs these different files are
called
modules and it's not just having a bunch
of code and randomly taking a chunk of
it and sticking it in another file what
you do whenever you make different
modules is you group similar code
together so say that you're making a web
app in like maybe it was a website and
you had a section where a user could
look at music and another one for movies
and another one for TV shows well you
would want to take all the movie related
code and break it up into its own file
so that way everything isn't jumbled all
together so let's actually go ahead and
make a quick example so as you guys can
probably already expect whatever file
API s is in right click the directory
and hit new javascript file you can name
it anything you want I'm going to name
mine movies dot j s so again this movies
dot J s file would be a separate module
so what we would want to do here is any
movie related code we would want to
stick in here and the rest of our
program can go in another file so just
so I have something I'm just going to
make a you know real quick function or
just like print out two different movies
so print Avatar console dot log and I'll
print out like the name in the rating
alright so avatar pg-13 I think it's
pg-13
and let's make one more so function a
I'll print Chevy by the way I think I
saw this I think I said this I saw
chappie the other night and a pretty
good movie how they recommended so
chappie and I believe this is rated R I
think so
I remember they said the effort a couple
times so whatever all right so here's
the thing we have a couple of different
files and they each have little bit of
code related to you know whatever the
file is and we want to pretty much take
this code and use it in our main file or
include it in a different file so how do
we do that well but the terminology the
correct terminology is what we're doing
is we're going to export some code from
movies and import it into app j/s so
that's what we're trying to do take this
code and include it right here now
here's the thing whenever we do this all
this code just doesn't get exported by
default we can actually say what code do
we want to export now the code that gets
exported is determined by a variable
called module dot exports now once you
type this keyword what you can do is you
can tack on a variable and this can just
be any custom variable you want so I'm
going to say that I'm going to export
this avatar function in I'm not going to
export this chappie one maybe I want
this chappie one be private maybe I'm
still working on it anyways it's not
ready to use in another file so anyways
I'm going to make a variable called
avatar and you just set this equal to
whatever you want to export so print
Avatar and you don't have the
parentheses so there you go so now
whenever something tries to import
movies is it says okay whenever I'm
trying to import this you obviously only
want to in or excuse me
export this function right here so
that's that and let's see how to import
it so whenever you're importing another
module what you do is you set it equal
to a variable
so I'm going to set this equal to movies
and after that you use the require
keyword which is pretty much saying we
are requiring a module we are requiring
a file to include in this one so the
parameter that this takes is this period
forward slash movies
now what this syntax it may look a
little confusing so I'll break it down
this dot forward slash this is just a
syntax that says look in the same
directory that I am at for a file called
movies so we obviously know obviously no
ap is is in this directory public so
it's going to scan this directory and
it's going to look for a file called
movies J s if you're like a Bucky you
forgot to type the J s extension might
fix that for you actually whenever
you're importing modules never include
the dot J s extension and this is to do
with a couple different things first of
all this is kind of background
information you really don't need to
know it but some of your systems get
confused by the file extensions because
like a browser can't have access to your
file system so it doesn't really arm do
a good job of looking at the extensions
and also another thing I want to point
out while I'm talking about this you
guys may be like alright so what's the
point of this dot forward slash can I
just rate movies well later on I'm going
to show you guys how to import something
called core modules which is essentially
a modules that are already built into
the language for you and whenever you
import core modules that's when you use
just the plain key word instead of the
path so again just remember right now
whenever you want to import a module we
were going to do is you're going to use
the required keyword and then the path
in the dot forward slash means look in
the same directory and do not include
the dot J s extension so again what this
line of code does is it says okay I'm
going to require code from this file so
it's going to hop over to this file go
doo-doo-doo-doo alright what are you
trying to export this right here I'm
going to grow
have everything right here and pretty
much plop it in this variable so now
with this movie's variable remember this
is essentially equal to the other module
remember we made a variable called
avatar which was a function and we can
run it just like expected so again
whenever you run app j s since it
imported everything we told it to export
for movies that yes it works fine and
obviously here's the thing it may just
may see a little bit so since we only
chose to export avatar and not print
chappie if we ever try to do something
like movies dot print chappie that's not
going to work so this is essentially the
same as having public and private
methods so maybe this I don't know maybe
you only wanted to access this function
from inside this module so that is how
you can accomplish that so that is the
bare basics of modules but there's
actually a lot more to cover so now that
we understand the basics we can hop into
the little more detailed stuff and I'll
show you guys some other cool ways in
maybe easier ways to export and import
modules so anyways thank you guys for
watching and we can subscribe yada yada
tomato tomato see you next time