All language subtitles for 019 Defining Functions Inside Of Functions_en

Now, another thing related to functions

which you'll see quite a bit in this course

is that you can define functions inside of functions.

Now, when writing vanilla JavaScript code,

this often might not make too much sense

but it will make more sense in the context of React,

as you will see later.

Nonetheless, you can define a function,

for example, called init,

which then contains another function defined inside of it,

for example, a function named greet

which console logs something.

Then, inside of init,

you can execute greet

but you can't execute greet outside of init.

Because greet is now defined inside of init

and therefore it's scoped to this init function,

which means it's only available in there,

just as a variable you would define in here

would only be available inside of init

and not outside of it.

And therefore, inside of init you can execute it

but outside of init you can't.

Here though, we can execute init

because init is scoped to the overall file

since init is not nested into another function.

And therefore, with this code here,

if you reload this,

you will see that we do output hi,

so that this code here does get executed

because in the end, we're executing this function,

which then internally calls greet,

which is this function here that was defined inside of init.

So, you are able to define and execute functions

inside of other functions.

And again,

whilst this is not something you might be doing too often

in just JavaScript,

it is something you'll do a lot

as you will see throughout this course

when writing React code.