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In this video, I want to add in a couple little notes around syntax of interfaces.

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So once again, when we define an interface, we're going to list out all the different property names

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and types that we expect, something that is a vehicle to have.

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We are not only limited to expressing primitive values inside of here, we can instead express any different

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type we want to inside of an interface.

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So, for example, let's say instead of the year property being a number, we instead want this to be

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a more complex object, like an instance of a date to do so.

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I'm going to replace no with simply date like so now in order for old Civic to be considered to be a

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vehicle, you'll notice that we've got an area down here.

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We have to update its definition.

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So instead of your being a simple number, I'm going to instead assignment an instance of a date like

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so as soon as I do so, that area down here goes away.

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So once again, we are not limited to just basic values or primitive values inside of an interface definition.

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We can assign any type inside there that we want.

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That also includes functions, so let's say that we want to say that in order for old Civic to be considered

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to be a vehicle, we want it to also have a function called summary.

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So in other words, I want this object right here to have a property or a function called summary.

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And if we call it maybe it should return a string that summarizes some different facts about the vehicle.

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To express that, I'm going to add in another property on vehicle.

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Called summary like so.

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And then instead of immediately putting in a set or a comma or see a colon right there, I'll put in

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a set of parentheses and then a colon right after it.

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And I'm going to label what I would expect the summary function to return.

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So in this case, maybe it's going to return a string that summarizes some different facts about the

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car.

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So this right here says that anything that wants to be a vehicle has to have a function called summary

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that returns a string.

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If we then go back down to the bottom again, you'll notice we have an area down here as well.

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So now it says that we do not have a summer property inside of old Civic.

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So to fix this up, we would have to add in a summary function that satisfies this type right here.

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So it has to be a function with no arguments.

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That returns a string and so we can add it on like so.

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So now to return some information about this vehicle, we could return about like.

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Name.

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Is this name like so and again, notice the yes, 2015 tablets drink here, so I am using tactics.

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So now that my object has a summary function that returns a string, it once again qualifies as being

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a vehicle.

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So if I go back down to the bottom of the pile again, that air has now gone away and now inside of

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my print vehicle function, rather than trying to pull off all these different properties one by one,

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I can instead rely upon that summary function.

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So I can call something like console that log.

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Vehicle dot summary like so.

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All right, so again, just two notes here.

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First off, we can use any type inside of our interface definition we want.

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We are not limited just to primitive values.

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Second important note is that inside of our interface definition, we can express functions inside there

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as well.

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So let's take a quick pause right here in the next video, I want to share two more important notes

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with you around basic syntax of interfaces.

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A quick pause and I'll see you in just a minute.