सिर्फ दिखाएँ
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
We talked a lot about services in this module.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And I hope you saw how services can clean our app up,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
make the code a bit leaner,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
more centralized,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
easier to maintain.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
You don't have to build these complex output input
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
chains where you pass events and properties to get data
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
from component A to component B.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
It's much leaner now.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Let me show you how much we actually saved.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Let's say that if we click on the button here in the account component,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
for some reason,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
we want to output something in the new account component.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Normally,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
without services,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
we would have to emit an event in the account component
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
that something was clicked or something happened so that we changed the status,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
for example.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
We would have to catch the event here in app account.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
As a side note,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
we can of course remove these events here.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
They aren't triggered anymore.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So we would have to catch these events here.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And then we would have to pass the new data
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
down via property binding to the component
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
where we want to handle it.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Pretty complicated.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And building these chains of property and event binding is not the most convenient
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
way of writing code.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
It's so much easier with services.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Let's say in our account service here.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
we want to provide some event which we can trigger
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
in one component and listen to in another.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So we could simply add the status
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
updated event,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
which could be a new event emitter,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
which we import from addAngularCore.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So make sure to add this import at the top,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
which will pass on the new event,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
excuse me,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
the new status,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
so a string.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And yes,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
we could trigger it now here in the update status method.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
But we can also,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
since we inject the account service here where we set the new status,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
call account service status updated
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
and emit this with the new status.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So now I'm emitting an event I set up in the service.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And as a side note,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
later in the observable section,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
you will learn about another construct you can use
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
to submit or to emit.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
You've made events and subscribe to it instead of using the event emitter.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
But for now,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
that's absolutely fine.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So here we are emitting an event.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Again, the event emitter lives in our service.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And in the new account,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
I now want to listen to it.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So here,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
let's say I want to throw an alert.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So I will do this in the constructor for now.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Access my account service.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And now for the status updated event here,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
I will subscribe to it because event emitter in the end just kind
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
of wraps and observable.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So here I could then receive the new status,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
which I know will be a string.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And then I will simply throw an alert where I say new status,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
status,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
something like that.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So now I'm not building any chain of property
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
and event binding.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
I do have cross -component communication through
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
a service with the event emitter.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And you can see this,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
if I click a button here,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
they actually got opened on another window,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
but you see,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
this alert was thrown with the new status unknown.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Same here,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
inactive.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Active.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
So now we're communicating between components through a service,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
which really can save you a lot of time.
3:40
S… Speaker 1 (116. Using Services for Cross-Component Communication)
And with that,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
I hope you saw a lot of reasons why services can be very helpful and
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
how you can use them to your advantages.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
Make sure to use the right amount of instances.
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
And if you inject services into services,
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
make sure to provide the service on the app module level and to
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S… Speaker 1 (116. Using Services for Cross-Component Communication)
add add injectable to the service where you want to inject it in.
4:02
S… Speaker 1 (116. Using Services for Cross-Component Communication)
Let's move on to some assignments now.

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