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Alright, time to correct the
exercise. So, well, let's
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start. Uh so on the left here I
have my console running with
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nodemon in quiet mode. So I'm
going to remove that and so
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we're going to start. So we
have to create a bank account
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with basic operations, add
money and withdraw money first.
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So all right? I'm going to
create a class that I'm going
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to call bank account and I will
have a private balance this way
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it's protected and noone can
access the balance outside of
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the bank account class so this
is going to be a number so I'm
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going to create a constructor
that will be able to receive
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the balance and I'm just going
to initialize it with this
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value so it means that outside
for example I could create an
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account one and now do a new
bank account and I could send
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my balance so for example 14,
000 now I want to be able to
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add money and withdraw money so
I'm going to create two
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functions I'm going to create
deposits and I'm going to
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create withdraw so deposit is
it going to return something no
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technically no and withdraw
nope it's not supposed to
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return anything it just suppose
to do an operation so deposit
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well you have to tell how much
and we're going to receive an
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amount that will be a number
and we're just going to update
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the balance and add the amount
and technically we're good with
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the add money now with the
withdraw it's almost the same
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but we have to make sure that
we're not going to go under the
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minimum balance that is allowed
so by default we're going to
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suppose that you cannot go
under zero right so first we
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have to receive an amount again
here to withdraw.
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And we're just going to first
check if the balance minus the
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amount is still above zero so
if it's under zero then we're
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going to throw an error so
throw new error and we're going
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to write insufficient funds
otherwise we can update the
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balance and subtract the amount
and technically we're good with
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the withdrawing so now let's do
this one get the current
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balance so for now the balance
is private and that's perfect
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we're just going to create a
getter for the balance so it
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will be get balance and we're
going to return this dot
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balance and technically we're
good with this one so we're
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going to test this three first
so I'm just going to do account
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one. for example deposit 10 000
I'm going to log if I have
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50000 so account one. get
balance I'm just going to write
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balance before and see Okay.
Balance 3 thousand. So it seems
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to be working. Now I'm going to
try to withdraw some money. So
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account one dot withdraw and
I'm going to remove 50000 so
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this should work. Oh I have to
log it after.
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So balance after withdraw yes
zero okay we're good now we're
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going to try to withdraw one
more dollar and this should
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trigger an error okay so if I
save yes okay seems like I have
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a huge error so we have to to
catch this error so we're going
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to wrap this using try
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Then we're going to catch the
error.
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So the error here is of type any
So you think that this is
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of type error probably and that
would make sense. Um but as you
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can see you cannot force the
type for an error in a catch
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statement because there is
nothing that can really tell
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you that it's only this error
that is going to be thrown
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okay? Maybe you will have a
maximum stack exceed error for
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example if you made a bad loop
in your code or something. So
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type script assume that it
cannot really know what is
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going to be the error. So you
have to set the type unknown.
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You don't know what it's going
to be. And then we're going to
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print error.message to access
only the message. But you'll
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see that we will have an error.
So as you can see message does
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not exist on the type unknown,
okay? There is no such thing as
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message in an unknown type. So
you will have to tell
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explicitly that you know what's
the type of error now. And
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you're going to use something
that called the casting. So
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you're going to say that error
is actually of type error.
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You're going to the type of
error like this. This way you
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can call message on it because
message exists on the type
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error. Right? So this is called
the casting and sometime useful
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when at first you don't know
the type but you as a developer
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know for sure what it's going
to be. Okay? And now yes I have
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my error displayed. So I cannot
perform my operation. Okay
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cool. So it seems that add
money, withdraw money and get
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current balance are working. So
cool, so in the next video
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we're going to continue. See
you in the next one.