All language subtitles for 014 Using Modules 2_ Our Own Modules_Downloadly.ir_en

So what I wanted to show you

in this last video about the project

is that we can actually create our own module

and export something from them like for example a function.

Then import this function into another module

and then use that function there.

Okay, and so that is what we're gonna do in this lecture.

So let's say that we actually had

a bunch of different JavaScript files

in which we used this replace template function.

So right now we're just using it here in index.js.

We use it twice and that is why we have a function,

but imagine if we wanted to use this function

in multiple files.

Okay, so what we can do is to create a new module

and export that function from it

and then import it back here.

So, the first thing that you need to know

is that in Nodejs

actually every single file is treated as a module.

And so this index.js here actually is also a module,

which in this case imports other modules

and particularly these three.

Let's now create a new folder here,

which I'm gonna call modules

and then in here

I'm gonna create a file

which will be our module called replaceTemplate.js.

Okay, so let's grab our function here.

Actually, cut it out from here

and simply paste it here.

All right, now how do we actually export this function

from this module?

Well, there are different ways of exporting something

from a module

and we're gonna talk in depth

about all of this in another section later on.

But for now

all we're gonna do is to use module.export.

So in each module,

we have access to a variable called module

and on there we can set the export's property.

And that we then set to whatever we wanna export.

In this case, that is just this function.

So we're gonna get rid of this name

and so basically

what we're gonna assign to this export property on module

is simply this anonymous function.

I said anonymous

because right now this function does not have a name.

And so it's just an anonymous function

to be assigned to this export property

on the module object.

Again, that is an object that we have access to

in each and every Nodejs module.

And again,

later on you will learn

how that actually happens behind the scenes.

But for now,

let's just use it

and don't worry about why it works this way.

So this exports this function from the module.

Let's just go to index.js and import it.

And imports usually always happen at the top of the file

and after the core modules.

First, we have the core modules

and then we have our own modules.

We will do require and then our own module,

which is dot...

And remember in the require function,

the dot actually means the current location of this module.

So remember when we talked about the dir name variable here,

which is usually the one that points to the module's folder.

But in this case in the require function,

remember there is an exception

where this dot actually points to the location

where this module is in.

And so right now,

that is this root folder here.

And so from here we go to modules

and then in there we have replaceTemplate.

And again,

just as with the other modules,

we don't need the .js.

Now that is gonna return what we exported here

with module.exports.

What we have here, this code, this function,

is what will be exported from this require function call.

And so we can now save that into any variable

and give it a name that we want.

So we could just call it X if we wanted

or really whatever we wanted.

But instead I am just giving it this name

that we already had here

so that I don't have to change my code here.

So replaceTemplate is the name

that I wanna give to this variable

which is now this function.

And just like this,

we exported something from one module

and imported it into another one.

And so now if we restart our server,

everything should still be working.

But it actually does not.

We have some kind of error here.

And it says it cannot find the module.

And that's because I was stupid enough

to call this folder here modules.js.

I am sorry for that.

This one is of course

only supposed to be called modules.

And that's why it wasn't giving me the auto-complete here.

I was wondering why that was.

And now we know.

If it doesn't work for you,

just change the name here of this folder

and then everything should match and work as it should.

Let's reload and it still replaces everything as it should.

The same here of course.

And so yeah, we are now done with this project.

Congratulations, well done.

You are well on your way of learning Nodejs.

Now in the rest of the section

we're gonna talk a little bit

about the node package manager or npm.

And so we're gonna keep working a little bit

with this project

but not really adding any functionality.

Anyway, see you in the next video

where we're gonna start talking about npm.