Node.js Tutorial for Beginners - 6 - this Video Lecture | The Complete NodeJS Developer Course - Back-End Programming

alright guys let's go ahead and talk
about the this keyword th is I'm sure
you've seen it before and a lot of
people seem to be kind of confused by it
so I'll explain that really easily
whenever you see the keyword this it
just refers to the thing that called it
so that's even more confusing so let's
go ahead and look at an example and
it'll be a lot more clear so say that we
have a object Bucky and I'm just going
to throw a real quick I don't know I'll
make like a function like print first
name yeah my semi colon alright so we're
going to have one single function in
here a function and what is this
function going to do
well we're just going to log out two
pieces of information the first thing is
we'll just say something stupid like my
name is Bucky just so this function
doesn't feel completely worthless and
then what I'm going to do is I'm going
to log out one more thing right after
this I'm going to say I'm going to have
a test and I'm going to say is this
equal to Bucky so let me type one line
of code and I'll show you guys what's
going on if we take this object Bucky
right here and we call the function
print first name remember that I told
you guys in the very beginning of this
tutorial this keyword right here is just
the reference to whatever thing is
calling it so of course we can see print
first name what's calling it well Bucky
is calling it so this test is going to
print out true so well now if of course
it logs my name is Bucky and of course
it logs true right there so again one
more time this is just a reference to
whatever thing or whatever object is
calling it of course we can see really
clearly that Bucky is calling print
first name so that's easy enough to
understand I mean it's right there in
front of us
the
anything people get a little bit
confused about is this what happens when
we make a function if I type it
correctly I type it correctly all right
what happens when you make a function
that isn't clearly part of any object so
like do something worthless so we're
making this function and okay it's not
really like hard or inside of any object
so if we were to start logging some crap
out let me just put a little indicator
be like I'm worthless just so we have
some text to print out what happens is
this the default calling context
actually right this the the default
calling context is global what this
means is if we build a function and it
doesn't belong to any object its
global which pretty much means your main
entire program is going to call it so
this is no longer equal to Bucky I'll
just test if it's equal to global so I'm
going to call do something worthless and
check out what happens
so of course just like before we kept
that already explained it now when we
call do something worthless it's not
being called by an object like Bucky was
calling print first name it's being
called by I don't know what's being
caught by like the main program
well that refers to global so that's why
whenever we test it this is equal to
global so again one more time this like
I said is just a reference to whatever
thing is calling it it can be an
explicit object like we can see here
Bucky or we can just call it through our
main program which means global the
global program simple enough thank you
guys for watching and probably going to
go eat some Hot Pockets now see you guys
next time